For the lemon crepes: Whisk together the milk, eggs and vanilla in a medium bowl until smooth. Add the flour, sugar, salt and lemon zest and whisk until smooth. Set aside.
For the almond mascarpone filling: Combine the heavy cream, mascarpone, sugar and vanilla extract in a separate medium bowl. Using a handheld mixer, beat on medium until stiff peaks form, about 3 minutes. Fold in the chopped almonds.
Heat a medium saute pan over medium heat. Add a teaspoon of the butter and swirl the pan until the butter is melted and coats the pan (you can also use a pastry brush to brush softened butter into the pan). Add 1/4 cup of the batter and swirl the pan to coat the bottom with an even thin coating of batter. Cook for 2 minutes, gently flip the crepe and cook for another minute on the other side. Remove to a plate and continue with the remaining batter, adding more butter as needed.
To serve, place 1 heaping tablespoon almond mascarpone filling on one quarter of a crepe. Gently fold the crepe in half and then in half again making sort of a triangle. Serve 2 per plate, sprinkle with blueberries and dust with more lemon zest and powdered sugar. Drizzle with chocolate, if desired.