1. For blintzes: Combine flour, milk, 1/4 cup water, egg, Truvia® natural sweetener, and salt in a blender until smooth. Scrape down the sides; add the 2 tablespoons melted butter and pulse to combined. Set aside for at least 30 minutes.
2. For filling: Beat the ricotta and cream cheese in a medium bowl with an electric mixer until combined. Add the egg, Truvia® natural sweetener and lemon zest and beat until smooth.
3. Heat an 8-inch nonstick skillet over medium heat until a drop of water bounces briefly on the surface before evaporating. Quickly pour 2 tablespoons of batter into the center of the pan and swirl to coat the bottom and make a thin pancake. Cook until the bottom is golden, about 1 minute. Transfer to parchment or wax paper to cool. Continue with the remaining batter, stacking blintzes as they cool.
4. Preheat the oven to 350 degrees F. Spoon 2 tablespoons cheese filling on the lower third of the lighter side of the blintz, fold the sides over the filling and then fold in the bottom, rolling up into a tight package. Place blintz, seam side down, on a baking sheet. Repeat with the remaining pancakes and filling. Bake until puffed and heated through, about 20 minutes.
5. Meanwhile, stir together 1 cup blueberries, 1/8 cup water and Truvia® natural sweetener in a medium saucepan. Bring to a simmer over medium heat and cook, stirring frequently, until thickened and saucy, about 5 minutes. Stir in remaining 1/2 cup blueberries and lemon juice. Serve blintzes warm with the blueberry compote.