Preheat oven to 350 degrees. Line 10" round cake pan with parchment paper. Butter and flour sides (I use Baking PAM for this).
Use stand mixer with paddle attachment to beat butter and sugar until lightened in color, about 2 minutes.
Add egg and beat until well combined, scraping down sides as needed. Then, beat in egg yolk.
Beat in vanilla and almond extracts.
In a medium sized bowl, stir together flour, baking soda, baking powder, salt, and corn starch. Beat into butter mixture about 1/2 cup at a time, scraping down sides as needed.
Stir in 1/2 cup sprinkles.
Pour into prepared pan. Sprinkle remaining candy sprinkles (1-2 tbsp) over top of cookie, pressing down very gently.
Bake for 24-27 minutes, or until top is golden brown and a toothpick inserted into center of cookie comes out clean or with just a few crumbs.
Let cool completely before removing cookie from pan.