Heat your oven to 375°F (190°C). Line a baking sheet with parchment paper or a baking mat. You can also grease it lightly if you prefer.
In a medium bowl, whisk the flour, baking soda, baking powder, and salt. Whisking spreads the leavening evenly through the flour. This helps every cookie bake up the same way.
In a large bowl, beat the softened butter with the granulated and brown sugars. Mix until the blend looks light and creamy. This step traps air and gives the cookies a soft texture.
Beat in the eggs one at a time, then add the vanilla extract. Mix until the batter looks smooth and well blended. Scrape down the sides of the bowl once or twice.
Add the flour mixture to the butter mixture in the large bowl. Mix on low speed until the flour just disappears. Stop right there so the cookies don't turn tough.
Stir in the white chocolate chips and dried cranberries with a spatula. Spread them evenly so every cookie gets some of each. Keep a few chips aside for topping the dough.
Use a large cookie scoop to make mounds of dough on the baking sheet. Leave about 2–3 inches between them so they have room to spread. Press a few extra white chocolate chips on top for a pretty finish.
Bake for 9–11 minutes. Pull them out when the edges just start to brown. The centers may look a little soft, but they will set as they cool.
Let the cookies rest on the hot pan for 5–10 minutes. Then move them to a wire rack to cool completely. Bake the remaining dough the same way, using a cooled pan each time.