Sheet Pan Frosted Sugar Cookie Bars
Buttery soft sugar cookie bars baked in a 13x18 pan, frosted with vanilla buttercream and topped with rainbow sprinkles. The perfect birthday cake alternative!
Servings 35 bars
Equipment
- 1 Half sheet pan Or halve the recipe for a 9x13 pan
Ingredients
Sheet Pan Sugar Cookie
- 4 1/2 Cups (594g) all-purpose flour
- 1 tsp baking powder
- 1 Tbsp (10g) cornstarch
- 1 tsp salt
- 1 1/2 Cups (339g) unsalted butter, room temperature
- 2 Cups (400g) granulated sugar
- 4 large eggs, room temperature
- 1 Tbsp pure vanilla extract
- 1/2 tsp almond extract*
- 1/2 Cup (120g) sour cream*, room temperature
Vanilla Buttercream
- 1 Cup (226g) unsalted butter, room temperature
- 3 1/2 Cups (420g) powdered sugar
- 2 tsp pure vanilla extract
- 2 Tbsp whole milk, room temperature
- pinch of salt, or to taste
- 1 drop pink food color gel (optional)
Garnish
- 1/3 Cup rainbow sprinkles
Instructions
Make the Sheet Pan Sugar Cookie
- Preheat the oven to 350ºF (177ºC) and line a half sheet pan* (13x18 cookie sheet) with parchment paper. Be sure to leave a slight overhang of parchment paper if you plan on lifting the cookie out of the pan for decorating.
- In a medium bowl, add the flour, baking powder, cornstarch, and salt. Whisk together to combine and set aside.
- In the bowl of your stand mixer fitted with the paddle attachment (or with a large bowl and hand mixer) cream the butter and sugar together on high speed until light and fluffy, 2-3 minutes. Add the eggs one at a time on medium speed and mix until combined.
- Mix in the vanilla, almond, and sour cream on medium speed until combined. It will look curdled at this point, but don't worry – it will come together in the next step!
- Add the flour mixture and stir on low speed until combined and smooth. The dough will be slightly sticky but spreadable.
- Add the dough into your prepared sheet pan and use an angled spatula to spread it all the way to the edges in an even layer. Bake for 14-18 minutes, until the edges are just starting to brown and the center springs back slightly. It will bake a little more as it cools in the pan, and I bake mine for 15 minutes to get the perfect texture. Cool completely in the pan before decorating.
Make the Vanilla Buttercream
- Using the paddle attachment on your stand mixer (or hand mixer with a large bowl), cream the butter on medium-high until it’s creamy and light (almost white) in color. About 7 minutes.
- Turn the mixer to low speed and add the powdered sugar one cup at a time, scraping down after each addition and making sure each cup is fully incorporated before adding the next one.
- Add the vanilla, milk, and salt and mix on low speed for another minute until fully incorporated. Add the pink food coloring (if using) and mix on low speed until uniform in color.
Assembly
- If you wish, you can gently lift the sugar cookie out of the pan once cooled using the parchment paper overhang. I usually just leave mine in the pan for convenience and easy transport.
- Frost the sugar cookie with the vanilla buttercream using a small icing spatula. To create the look pictured, create rustic texture with the buttercream (basically make some swoops and c-shapes with the icing spatula) and top with rainbow sprinkles.
- When you're ready to serve, slice the giant frosted sugar cookie into bars!
Notes
*Almond Extract: I love the flavor of this cookie with a little almond extract but if you don't want to use it, sub in an equal amount of vanilla extract.
*Sour Cream: This is the key to making this giant sugar cookie super moist. If you don't have access to sour cream, you can omit it and bake the cookie for 1-2 minutes less. It won't be as moist but it will still be totally delicious.
*Half Sheet Pan: if you want to bake this in a smaller pan (like 9x13 or 12" round), simply halve the recipe.
Make Ahead Tips:
- You can bake the sheet pan sugar cookie ahead and store in the pan wrapped in plastic wrap at room temperature for 1 day. If you want to freeze it, be sure to wrap it really well and freeze for up to 2 months.
- The frosted sugar cookie can be stored at room temperature covered loosely with plastic wrap for up to 1 day.
- Once sliced, the sugar cookie bars can be stored in an airtight container at room temperature for up to 5 days.