In a medium bowl, combine the flour, cornstarch, baking soda, and salt. Set aside.
In a large mixing bowl, beat the butter, brown sugar, and granulated sugar until light and fluffy (about 2–3 minutes). Beat in the eggs one at a time, followed by the vanilla and almond extracts.
Add the flour mixture in portions, mixing on low just until combined.
Stir in the white chocolate chips. Gently fold in the frozen raspberries. Be careful not to over-mix, or the dough will turn pink.
Using a 3-tablespoon cookie scoop), portion the dough onto a parchment-lined baking sheet. Cover and chill the scooped dough for at least 1 hour (or up to overnight).
Preheat oven to 350°F (175°C). Place the chilled cookie dough balls a few inches apart on a lined baking sheet. (I bake 8 per sheet. Keep the remaining dough in the refrigerator until needed.) Bake 12–15 minutes, or until the edges are golden but the centers still look soft.*
Cool on the pan for 5 minutes before transferring to a wire rack to cool completely.
Notes
*If you chilled the dough longer than an hour, the cookies may need to bake for another minute or two.
Store in an airtight container at room temperature up to 3 days.