Entirely Elizabeth

0 Preheat oven to 350° F (177° C) and center the oven rack.
1 Fit an 8×8 baking dish with parchment paper and spray with non-stick cooking spray. Use 4 binder clips, one on each side, to hold the parchment paper in place.
Melting the Butter and Chocolate
2 Place the white chocolate chips and semi-sweet chocolate chips in two seperate heat safe bowls.
4 Melt the salted butter (two stick total) in a small saucepan and remove it from the heat once it begins to boil and sputter. 
5 Pour half of the butter over the white chocolate chips and the other half over the semi-sweet chocolate chips. Allow it to sit for 10 minutes.
6 Stir the butter and chocolate together until it has become a fully incorporated mixture and all the chocolate chips are melted.
Making the Blondie Batter
13 In a large bowl whisk together the butter white chocolate mixture and granulated sugar until light and fluffy.
14 Add the vanilla and eggs, whisk until incorporated.
15 Fold in the flour until the batter just begins to come together but is not fully incorporated.
12 Fold in the ¼ cup of white chocolate chips. Set aside.
Making the Brownie Batter
9 In a large bowl whisk together the butter semi-sweet chocolate mixture and granulated sugar until light and fluffy.
10 Add the vanilla and eggs, whisk until incorporated.
11 Fold in the flour until the batter just begins to come together but is not fully incorporated.
16 Fold in the ¼ cup of semi-sweet chocolate chips. Set aside.
Constructing the Blondie Brownies
17 Using a cookie scoop or a large spoon, scoop the batters into the baking pan making sure to alternate them.
21 Using a spatula or butter knife, carefully swirl the batters together to create a marbled pattern.
19 Bake for 30 to 40 minutes or until the top and edges are caramelized and brown. A toothpick test in the center should come out clean with few crumbs.
20 Allow the Blondie Brownies to cool for 30 minutes before cutting with a plastic knife into 12 equal slices.