Line your 9x11 baking sheet with parchment paper and set it aside. This makes for easy cleanup and prevents the cookies from sticking.
In a large bowl, whisk together the flour, baking powder, baking soda, cornstarch, and salt. Set this aside—it’ll soon meet your wet ingredients!
In a separate bowl, beat together the butter and sugar until light and fluffy.
Next, add in the egg, followed by the sour cream, vanilla, and almond extract. Mix it all up until smooth and well combined.
Now, slowly fold the dry ingredients into the wet mixture. Stir until a dough forms—don’t overmix!
Shape the dough into a ball, flatten it slightly, and wrap it in plastic wrap. Pop it in the fridge for 1 hour. This helps the dough firm up, making it easier to roll out and cut into shapes.
Once the dough is chilled, prep your surface with flour and grab your rolling pin. Roll the dough out to about ¼ inch thickness. Use a heart-shaped cookie cutter to make cute Valentine’s cookies, and place them on your parchment-lined baking sheet.
Preheat your oven to 375°F, and bake the cookies for 8-9 minutes, or until the edges are just starting to turn color. Remember, you want them to stay pale for that soft, iconic Lofthouse look—don’t overbake!
While the cookies are cooling (about 20 minutes), dye your buttercream frosting with a few drops of red food dye for a festive touch. Once the cookies are cool, spread a thin layer of frosting on each, and sprinkle with Valentine’s-themed sprinkles!