In a stand mixer fitted with paddle attachment, combine butter and sugar; beat on medium-high until light and fluffy, about 5 minutes. Add egg, vanilla, and almond extracts; mix until combined.

In a separate bowl, whisk together flour, cornstarch, baking soda, and salt. Gradually add dry ingredients to wet mixture; beat until just combined. Fold in sprinkles.

Using a 2-inch cookie scoop, form heaping two-tablespoon mounds. Place on a plate, flatten slightly, cover, and refrigerate for at least 2 hours.

Preheat oven to 350°F. Line baking sheets with Silpats or spray with cooking spray. Arrange cookie mounds, spaced at least 2 inches apart.

Bake for 8 minutes, edges set but cookies remain white and soft. Cool on baking sheet for 5 minutes, then transfer to a rack.

Store in airtight container at room temperature up to 1 week, or freeze for up to 3 months.