For the ricotta filling: Whisk together the ricotta, powdered sugar, cocoa powder and vanilla extract until light and fluffy. Fold in the chocolate and almonds. Cover and refrigerate for at least 1 hour and up to 8 hours.
For the blintzes: Whisk together the sugar and eggs until pale. Whisk in the milk and butter. Sift the flour, cocoa powder and salt onto a piece of waxed paper. Add the sifted ingredients to the wet ingredients and whisk until smooth. Cover and refrigerate for at least 1 hour and up to 24 hours.
Heat a skillet over medium heat and melt a little butter. Ladle a scant 1/4 cup batter into the skillet. Tilt to swirl the batter so it covers the bottom of the skillet. Cook on one side until small air bubbles form, the top is set and the bottom is golden brown. When done, carefully loosen the edges of the crepe, flip over and cook for 30 seconds longer. Slip out of the skillet onto a plate. Butter the skillet as needed and repeat until all the batter is used.
Turn each crepe so the golden brown side is up. Place 3 tablespoons ricotta filling in the middle in a 3 by 2-inch-wide mound. Roll once to cover the filling. Fold the sides into the center and continue rolling until completely closed. Repeat with the remaining crepes. You may have leftover filling; don't overfill.
Serve 2 blintzes per plate. Spoon some of the Warm Cherry Sauce over, sprinkle with powdered sugar and garnish with mint sprigs.
Warm Cherry Sauce:
Combined the reserved cherry juice, kirsch and enough cold water to measure one total cup of liquid.
Whisk together the sugar and cornstarch in a small saucepan until no lumps remain. Gradually whisk in the cherry juice mixture and cook over high heat until the mixture comes to a boil. Add the cherries and continue cooking until the sauce has thickened, stirring occasionally, about 5 minutes, remove from heat and add the lemon juice and almond extract. Serve hot or warm.