Mix 2 ¾ cups all-purpose flour, 1 ¼ teaspoons baking powder, ¼ teaspoon baking soda, ½ teaspoon salt, and 1 tablespoon cornstarch in a bowl and set aside.
In a large bowl with a hand mixer, or using a stand mixer, cream ¾ cup unsalted butter and 1 ¼ cups granulated sugar together on high speed until light and fluffy, about 4-5 minutes. Add 1 ½ teaspoons vanilla extract and ½ teaspoon of almond extract and mix for 10 seconds, then add 2 large eggs one at a time and mix on medium high. Finally, add ¾ cup sour cream and mix until blended, scraping down the sides of the bowl as needed.
Add the dry ingredients and mix on low speed in 2-3 batches until the dough just comes together.
Chill the cookie dough, covered, in the fridge for at least an hour, and up to 2 days.
Preheat the oven to 375°F / 190°C and line a baking sheet with parchment or a silicone baking mat.
Remove the dough from the refrigerator and let stand at room temperature for at least 15 minutes if it is too difficult to scoop. Scoop the dough out at about 1.5 tablespoon portions (correctly sized cookie scoops help here) and place on baking sheet 2-3 inches apart. After scooping out the dough, flour your hands and roll the dough into balls and replace on the baking sheet. Press down center of dough balls with thumb.
Cook for 8-10 minutes (mine usually took 9). Remove from oven and let them cool on the baking sheet for at least 5 minutes before moving to a cooling rack.
While the cookies are baking and cooling, you can make the buttercream.
For the strawberry buttercream:
First you will need to grind up the 1-ounce bag of freeze-dried strawberries. Pulse them in a food processor until they look like a powder. If you don’t have a food processor, you can also use a spice grinder/coffee grinder, but you’ll need to do it in a few batches.
In a large mixing bowl with a hand mixer or a stand mixer, cream the 1 cup unsalted butter and 2 cups of the powdered sugar together on high until light and fluffy, about 2minutes. Add the other 2 cups of powdered sugar, ½ teaspoon salt, and the powdered strawberries and continue mixing. If using a stand mixer, switch the paddle attachment out for the whisk attachment on this step.
Add 1 teaspoon vanilla extract and the ¼ cup of heavy cream and mix on high until fluffy and a spreadable consistency.
Spread the frosting onto the cooled cookies and add sprinkles if desired.
1) If you’re not a fan of strawberry, you can make these with vanilla buttercream instead. Simply replace the freeze-dried strawberries with an extra teaspoon of vanilla extract.2) You can use any milk for the buttercream, but heavy cream will give it the creamiest taste and consistency. I would avoid skim milk though.3) If you have trouble finding freeze-dried strawberries, they are typically located in the grocery store in the same area as raisins and other dried fruits. Or buy from Amazon here. Avoid using fresh or frozen strawberries, as they can add too much extra liquid to the buttercream.