Prepare Filling

Combine all ingredients in food processor and pulse until smooth. Cover and refrigerate until ready to use. (Can be made a day ahead.)

Prepare berry sauce

In a medium saucepan, combine blackberries, blueberries, sugar, and lemon zest. Bring to a boil over medium-high heat stirring constantly. Cook 2 minutes until berries have softened. Remove from heat.

Purée berry mixture until smooth with an immersion blender or transfer to a blender and purée until smooth. Strain through a fine mesh strainer to remove the seeds and pulp.(Can be made a day ahead.)

Gently fold in raspberries.

Prepare Crepes

Add ingredients to blender jar in the order listed, cover and blend until smooth. Refrigerate overnight or for 1 hour prior to cooking. (Or you can strain out any lumps and use immediately.)

Heat an 8-inch non-stick skillet or crepe pan over medium heat and lightly coat with butter or cooking spray. For each crepe, pour ¼ cup batter into the center of the skillet and immediately rotate the pan until the batter covers the bottom of the skillet in a thin layer. Cook until light brown and the top begins to dry out, approximately 1 minute. (Don’t cook the other side for blintzes.)

Stack completed crepes on a plate separated by wax paper or parchment paper.

Make the blintzes

Place a crepe browned side up on a work surface. Spoon 3 tablespoons filling onto the bottom half of the crepe. Fold bottom over filling. Fold in sides, and roll up burrito style. Set aside, seam down. Repeat with remaining crepes and filling.

Heat 1 tablespoon butter and 1 tablespoon vegetable oil in frying pan over medium heat. Fry blintzes three at a time until golden, about 2 minutes per side. To serve spoon warm sauce over top, and dust with powdered sugar.