Prep: Preheat oven to 375°F and line two cookie sheets. (Note: Do not preheat yet if you plan on chilling the cookie dough.)
Cream wet ingredients: Beat butter with a hand mixer on medium-high speed until smooth; slowly pour in both sugars while continuing to beat. Add egg and vanilla and beat on medium-low speed just until smooth.
Combine cookie dough:Combine flour, baking powder, baking soda and salt in a small bowl, then add to the egg mix and beat on low speed just until combined (do not overmix!). Fold in cranberries and white chocolate chips or chunks.
Shape cookies: Using a cookie scoop, shape cookie dough balls of about 1.5 inches in diameter, and space them out on 2 cookie sheets. Either chill 30-60 minutes for thicker, softer cookies. Or bake right away for crispier and chewy cookies.
Bake cookies: Bake the cookies in the preheated oven for 10-13 minutes, or until they are browned to your liking (a longer baking time will make them crispier, a shorter time more underbaked and fudgy). Cookies will be soft when they come out of the oven, so cool on the cookie sheet for 5 minutes before removing them to a cooling rack to cool completely.
Notes
Fixing spread out cookies:
If your cookies spread too much (can happen due to ingredient differences, oven differences, altitude, room temperature, etc), use two large spoons to gather/push the cookies together RIGHT as they come out of the oven. You have to be incredibly fast here or it won't work, but I've fixed many a spread out cookie this way.
Freezer instructions:
To freeze unbaked cookie dough: Shap the dough balls, then flash-freeze them on the baking sheet until firm (this will take an hour or so) before transferring them to a freezer bag. Label with the name and use-by date, then freeze for up to 2 months.To bake frozen cookie dough: Remove as many dough balls as needed from the freezer bag, then place on a lined cookie sheet and bake as directed in the recipe - no need to thaw! The cookies will take 3-5 minutes longer in the oven and may come out thicker. To freeze baked cookies: Cool the cookies completely, then either wrap them individually in plastic wrap to freeze in freezer bags, or freeze in layers in containers, separating each layer with parchment paper. Label them with the name and use-by date before freezing them for up to 3 months.To defrost frozen baked cookies: Remove as many as you need from the freezer, unwrap them and defrost them on a wire rack on the counter for 1-2 hours.