Cream Butter & Sugars:
In a large bowl, beat the softened butter, brown sugar, and granulated sugar together on medium speed until creamy (about 2 minutes).

Add Egg & Vanilla:
Mix in the egg and vanilla. Scrape down the sides of the bowl and mix again until fully combined.

Mix Dry Ingredients:
In a separate bowl, whisk together the flour, cornstarch, baking soda, and salt.

Combine Wet & Dry:
Slowly mix the dry ingredients into the wet mixture on low speed until a thick dough forms.

Add Mix-Ins:
Fold in the white chocolate chips and dried cranberries. Cover and chill the dough for at least 1 hour (up to 3–4 days).

Preheat & Shape:
Preheat oven to 350°F (177°C). If the dough is very firm, let it sit at room temp for 30 minutes. Scoop 1.5 Tbsp of dough and roll into balls.

Bake:
Place dough balls on lined baking sheets, 3 inches apart. Bake for 11–12 minutes until the edges are lightly golden. Centers will look soft.

Cool & Garnish:
Let cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack. Press extra white chocolate chips and cranberries on top while warm, if desired.