Divide the ½ cup of fresh blueberries between 16 cavities of a mini ice cube tray. Use the back of a spoon to mash the blueberries firmly into each cavity.

Place the tray flat in the freezer for at least 3 hours or overnight, until the blueberry centers are completely solid.

Beat the softened butter, brown sugar, and granulated sugar together until light and creamy.

Add the eggs and vanilla extract and mix until combined.

Add the flour, baking soda, salt, and cornstarch. Mix just until a cookie dough forms.

Fold in the white chocolate chips and the ¾ cup of fresh blueberries.

Divide the room-temperature dough into 16 equal portions, about 3 ounces or 85 grams each.

Flatten one portion of dough in your palm. Remove one frozen blueberry center from the tray and place it in the middle of the dough.

Bring the dough up and around the sides of the frozen blueberry center so it is almost covered, leaving a little of the blueberry showing on top. Pinch the dough firmly around it. Repeat with the remaining dough and blueberry centers.

Place the stuffed dough balls on a tray and refrigerate for 30 minutes.

While the cookies chill, preheat the oven to 350°F and line the baking sheets with parchment paper.

Make the crumble by stirring together the flour, granulated sugar, light brown sugar, and salt in a small bowl.

Add the melted butter and vanilla extract. Toss gently with a fork until the mixture forms distinct, chunky crumbs. Set aside.

Arrange the chilled cookies on the prepared baking sheets, leaving plenty of room between them.

Bake for 7 to 8 minutes, until the cookies have started to spread.

Carefully remove the baking sheets from the oven. Use the flat bottom of a glass or metal measuring cup to gently press down on the center of each cookie and flatten the dome.

Pile a generous amount of crumble topping over the flattened center of each cookie.

Return the cookies to the oven and bake for another 5 to 6 minutes, until the crumble is lightly golden brown.

Let the cookies cool completely on the baking sheets so the blueberry centers can set.

Melt the white chocolate wafers in the microwave in 15 second bursts, stirring after each one.

Transfer the melted white chocolate to a resealable plastic bag and snip a tiny piece from one corner. Drizzle it over the cooled cookies and allow it to set.