Preheat oven to 350 degrees. Line an 8x8" pan or baking dish with parchment paper. Set aside.

In a bowl, whisk together the flour, baking powder and salt. Set aside.

In a mixing bowl, add the melted butter, brown sugar, egg and vanilla. Whisk together until smooth and thick.

To the butter mixture, gradually add in the flour mixture a few spoonful's at a time. Use a large whisk or electric hand mixer to mix the batter. Mix all the dry ingredients until fully incorporated. Batter will be very thick.

Fold in the lemon zest, 1 cup of white chocolate chips and 1 cup of the raspberries. (Reserve 1/2 cup of raspberries and 1/3 cup of white chocolate chips for topping.) Use a rubber scraper to gently fold together until just combined. (Don't use the electric mixer for this step, as it will mash the raspberries.)

Spread the batter into the prepared pan using a rubber scraper or offset spatula. Top the batter with the reserved white chocolate chips and raspberries.

Bake at 350 degrees for 40-45 minutes or until center of blondies are completely set and the edges are golden brown.

Let cool for 20-30 minutes before cutting into squares.