Preheat oven to 350°F. Line a large baking sheet with parchment paper. 

In a large mixing bowl, whisk together butter, sugars, milk, and vanilla until creamy. Add flour, corn starch, baking soda, and salt. Use a wooden spoon or rubber spatula to fold dry ingredients into wet until a soft dough forms. Fold in white chocolate chips. Cover and refrigerate dough for at least 1 hour.

Use a 1.5 tbsp cookie scoop to distribute dough on to a lined baking sheet. Top with 3-4 mini Cadbury eggs and a few additional white chocolate chips. Bake for 12 minutes until tops are light golden brown. The centers may feel a bit underdone, but they will continue to bake out of the oven. Add additional mini Cadbury eggs while still warm, if you prefer. Allow cooling on the baking sheet for 10 minutes before transferring to a wire cooling rack