Line two rimmed baking sheets with parchment paper.
In a large bowl, whisk together the melted butter, granulated sugar and brown sugar.
Add the vanilla and egg and whisk until combined.
In a medium separate bowl, whisk the flour, cornstarch, salt and baking soda.
Add the dry ingredients to the liquid ingredients and fold until a dough forms.
Fold in 3/4 cup of the chocolate chips.
Carefully fold in the raspberries, only maybe 4 mixes, so that the raspberries don’t dye the dough.
Cover the bowl with plastic wrap and refrigerate for 1 hour.
Scoop 1 1/2 tablespoons of cookie dough and place onto the baking sheet. Repeat with remaining dough and leave a few inches apart from each cookie on the baking sheet. There should be 12 cookies per baking sheet.
Repeat with scooping a second pan of cookie dough.
Set the second pan into the fridge until ready to bake later. I recommend baking only 1 pan of cookies at a time for even baking.
Bake each pan for 13-15 minutes until cookies are lightly golden around the edges.
Immediately after the cookies come out of the oven, place 2-3 white chocolate chips (from the remaining ¼ cup) on top of each cookie.
Let cool completely on the pan before storing in a container or ziplock.