Preheat oven to 350F. Line an 8x8 inch baking dish with parchment paper, leaving overhang on two sides for easy removal. Lightly grease the parchment.
In a large bowl, whisk together the almond flour, coconut flour, granular erythritol, baking powder, and salt. In a separate bowl, whisk the melted butter, eggs, and vanilla extract until smooth.
Pour the wet ingredients into the dry and stir until a thick batter forms. Gently fold in about two-thirds of the white chocolate chips, reserving the rest for the top.
Spread the batter evenly into the prepared dish. Scatter the fresh raspberries across the top, pressing some of them gently into the batter. Sprinkle the remaining white chocolate chips over the surface.
Bake for 25 to 28 minutes until the edges are golden and set but the center still looks slightly underdone. The blondies will firm up as they cool. Do not overbake or they will become dry.
Let the blondies cool completely in the dish, then lift them out using the parchment overhang. Dust lightly with powdered erythritol and cut into 12 squares. These are best served at room temperature.
