Preheat oven to 350°F. Line 2 large baking sheets with parchment.
Zest and juice 2 lemons, and set aside. One lemon will likely be enough for 1 tablespoon of juice.
Cream butter and sugar together.
Add egg and vanilla and mix thoroughly.
Measure dry ingredients together.
Add to butter and egg mixture and mix until just combined.
Add lemon juice and zest and mix until just combined.
Fold white chocolate chips into the batter.
Refrigerate for at least 4 hours, preferably overnight.
Scoop dough into 8 balls and arrange on two trays.
Bake for 12-14 minutes, removing when the cookies are browning around the edge and just set on top. For crisper cookies, bake an additional 3-5 minutes.
Let cool on baking sheet for 10 minutes before removing and allow to cool on a cooling rack for another 30 minutes.
Once fully cooled (or right before serving), dust with powdered sugar.