Soft, chewy sugar cookie bars topped with a thick layer of vanilla buttercream and sprinkles. No rolling or chilling required for this easy recipe!
- Cornstarch Tenderization: Interrupts gluten development to guarantee a melt-in-your-mouth, velvety crumb that stays soft for days.
- Yolk-Enriched Matrix: The addition of a single extra egg yolk adds fat and emulsifiers, creating a dense, chewy texture instead of a cakey one.
- Zero Chill Time: Skipping the fridge step means the butter remains perfectly emulsified, allowing the bars to go from mixing bowl to oven in fifteen minutes.
I remember sitting on the linoleum floor of my aunt's kitchen in 1998, peeling dried pink frosting off my knuckles while the scent of warm butter hung heavy in the air. We had spent three hours cutting out star shapes, half of which lost their points during the frantic transfer.
It got annoying fast.
That is why these thick, press-in-the-pan bars are hands down the superior way to get your sugar cookie fix. While I adore classic Soft Cut-Out Sugar Cookies, this sheet-pan version is infinitely faster and delivers a much more satisfying chew.
The magic here lies in the science of starch gelatinization and moisture control. By incorporating a touch of cornstarch, we interrupt the gluten development, ensuring the crumb remains incredibly tender and soft rather than turning dry or bread-like. We also use an extra egg yolk to enrich the protein matrix, which yields a dense, fudgy bite that clings to your teeth in the best possible way.
No chilling required.
I tested these in a cheap, dark non-stick pan, and the edges scorched before the center could set. Switch to a light-colored aluminum pan like USA Pan for an even bake, ensuring the heat distributes gently across the entire batch.
When you spread the thick, sticky dough into the pan, it will look alarmingly thin. Do not panic; just use your palms to press it flat, and watch it puff into a glorious, golden slab in the oven, reminiscent of my favorite 1-Bowl Salted Butterscotch Blondies but with a festive, birthday-cake flair.
Frosted Sugar Cookie Bars
Ingredients
- 1 and 1/2 cups (188g) all-purpose flour (spooned & leveled)
- 1 teaspoon baking powder
- 1/4 teaspoon baking soda
- 1 and 1/2 teaspoons cornstarch
- 1/4 teaspoon Diamond Crystal kosher salt (or 1/8 teaspoon table salt)
- 1/2 cup (8 Tbsp; 113g) unsalted butter, softened to room temperature
- 3/4 cup (150g) granulated sugar
- 1 large egg + 1 egg yolk, at room temperature
- 2 teaspoons pure vanilla extract
- 1/4 teaspoon pure almond extract
- 6 Tablespoons (60g) rainbow sprinkles (jimmies, not nonpareils)
- 3/4 cup (12 Tbsp; 170g) unsalted butter, softened to room temperature (for the buttercream)
- 2 and 1/4 cups (270g) confectioners’ sugar (for the buttercream)
- 3 Tablespoons (45ml) heavy cream or half-and-half (for the buttercream)
- 1 teaspoon pure vanilla extract (for the buttercream)
- 1 pinch of salt, to taste (for the buttercream)
- 1 drop gel food coloring (optional)
- 2 tablespoons extra sprinkles for decorating (optional)
Directions
- Preheat the oven to 350°F (177°C). Line a 9-inch square baking pan with parchment paper, leaving a generous overhang on the sides to act as a sling later.
- In a medium bowl, whisk together the flour, baking powder, baking soda, cornstarch, and salt until completely uniform.
- In a large bowl or stand mixer fitted with the paddle attachment, cream the softened butter and granulated sugar on medium-high speed for 3 minutes until the mixture is pale and fluffy. Beat in the whole egg, egg yolk, vanilla extract, and almond extract, scraping down the sides of the bowl with a silicone spatula to ensure even mixing.
- Turn the mixer to low and gradually add the dry flour mixture, mixing just until the flour disappears and a thick, sticky dough forms. Gently fold in the rainbow sprinkles using a spatula so they do not bleed.
- Transfer the sticky dough into the prepared pan and use lightly floured fingers or an offset spatula to press it into an even, flat layer.
- Bake for 25 to 26 minutes, or until the edges are just barely beginning to turn a pale golden brown. The center will still look quite soft and underdone, but it will firm up beautifully as it cools.
- Place the pan on a wire cooling rack and let the bars cool completely before frosting. The center will sink slightly as it cools, which is perfectly normal.
- To make the buttercream, beat the softened butter in a clean bowl for 2 minutes on medium speed until smooth. Add the confectioners' sugar, heavy cream, and vanilla, beating on low for 30 seconds before cranking the speed to medium-high for 3 full minutes to whip air into the frosting. Adjust with extra cream or sugar if needed, add a pinch of salt to balance the sweetness, and stir in gel food coloring if using.
- Use the parchment sling to lift the cooled slab out of the pan. Spread the buttercream evenly across the top, scatter extra sprinkles over the surface, and slice into 16 squares using a sharp chef's knife wiped clean between each cut.
Notes
Keep these essential tips in mind to ensure your cookie bars turn out perfectly tender and beautiful every single time:
- Brand & Conversion: We recommend using Diamond Crystal kosher salt. If you only have standard table salt, cut the measurement in half (use 1/8 teaspoon instead of 1/4 teaspoon) to avoid an overly salty cookie base.
- The Science of Tenderness: Cornstarch is our secret weapon here. It dilutes the flour's protein content, preventing excessive gluten development and keeping the bars incredibly soft and chewy for days.
- Workflow Warning: Do not overbake these bars! If you wait until the center looks completely firm and browned, they will dry out and lose their signature fudgy texture. The center should still have a slight jiggle when you pull them from the oven.
- Sprinkle Selection: Stick to traditional rod-shaped rainbow sprinkles (jimmies). Tiny round nonpareils will dissolve and bleed their dye into the wet dough, turning your beautiful bars a muddy gray color.
- Make-Ahead Strategy: You can bake the cookie base and whip up the frosting a day in advance. Keep the un-frosted slab covered at room temperature, store the buttercream in the fridge, and let the frosting sit on the counter for 30 minutes to soften before spreading.
Serving Suggestions
These sweet, buttery bars pair beautifully with items that offer a sharp contrast in temperature, acidity, or bitterness:
- Serve alongside a bitter, dark roast espresso to cut through the intense sweetness of the vanilla buttercream.
- Pair with a bowl of tart raspberry sorbet; the bright acidity of the berries beautifully balances the rich, buttery profile of the cookie.
- Crumble a few cooled bar pieces over a scoop of salty caramel ice cream for an amazing play on sweet and salty textures.
- Serve these at a party alongside our vibrant Confetti Sprinkle Cupcakes for a visually stunning, double-sprinkle Desserts table.
- Top with a few fresh, slightly crushed blackberries just before serving to add a juicy, sharp contrast to the creamy frosting.
Storage and Reheating
Once sliced, these bars should be kept in a single layer inside an airtight container. If you must stack them, place a sheet of parchment paper between the layers so the buttercream doesn't turn into a smudged, sticky mess.
At room temperature, they will remain perfectly soft and moist for up to 2 days. After that, the starch retrogradation begins to set in, making them slightly firmer.
For longer storage, keep them in the refrigerator for up to 5 days. The butter in the frosting will firm up in the cold, so we highly recommend letting them sit on the counter for 15 minutes before taking a bite.
You can also freeze the frosted bars for up to 3 months. Thaw them overnight in the refrigerator, and let them come to room temperature to restore that signature melt-in-your-mouth texture.
Ingredient Substitutes
If you need to make adjustments based on what is in your pantry, try these tested substitutions:
- All-purpose flour → 1:1 Gluten-Free Baking Flour: Use an equal weight (188g) of a high-quality blend containing xanthan gum, and let the dough rest in the pan for 10 minutes before baking to allow the rice flour to fully hydrate.
- Heavy cream → Whole milk: Swap at a 1:1 ratio in the buttercream, but add it one tablespoon at a time, as milk is thinner than cream and can easily make your frosting too runny.
- Unsalted butter → Salted butter: Use an equal amount (113g for dough, 170g for frosting), but completely omit the added kosher salt from both the cookie dough and the buttercream to prevent over-salting.
- Almond extract → Coconut extract: Swap at a 1:1 ratio (1/4 teaspoon) to give the cookie base a subtle, tropical undertone that pairs beautifully with the vanilla.
- Granulated sugar → Light brown sugar: Swap at a 1:1 ratio (150g) in the cookie dough; this will yield an even chewier, moisture-rich bar with a subtle caramel flavor profile.
There is something deeply comforting about a thick slab of frosted cookie covered in rainbow sprinkles. It brings back all the joy of childhood baking without any of the tedious rolling and cutting.
