Place a bowl and the beaters from an electric mixer in the fridge. This is for whipping the cream later, as heavy cream whips best when it's very cold.
Slice the tops off each berry, and then slice each berry vertically in half and then into eighths.
Toss the berries with 1 tablespoon of the granulated sugar in a bowl, then set aside.
In a blender, add the milk, eggs, remaining 2 tablespoons of sugar, flour, salt, and 4 teaspoons of the melted butter. Save the rest of the butter for greasing the crepe pan.
Purée the mixture on high for about 30 seconds, then turn off the blender and let it rest for at least 5 minutes. You can also let it rest overnight in the fridge. The longer the batter rests, the more tender your crepes will be.
Warm your crepe pan or nonstick skillet over medium heat, and brush with some of the melted butter.
Ladle a 1/2 cup of the batter into the crepe pan, and then tilt the pan in a circle until the batter covers the surface.
Cook the crepe on the first side until it easily releases when you run a spatula around the edges. Loosen the entire crepe with the spatula before attempting to flip it.
Flip the crepe, then use the spatula to smooth it out if it wrinkled while flipping. Continue to cook on the second side until golden brown spots form.
Remove the crepe from the pan and place it on a paper towel-lined plate. Cook the rest of the batter (you should get about 5 more crepes if you're using a standard 10-inch crepe pan).
While the crepes rest, pour the heavy cream in the cold bowl from the fridge. Connect the beaters to an electric hand mixer and beat the cream until soft peaks form, about 4 minutes.
Add the powdered sugar, sour cream, and vanilla, and continue to beat the cream until the mixture is light and fluffy.
To serve, Place each crepe on a plate and spread 1/6 of the cream down the center of each in a line. Top with a spoonful of the berries. You can either fold the crepes into quarters or roll them up to serve. Spoon any leftover berries over the top of the crepes and serve.
