10 ounces frozen blueberries
1/4 cup brown sugar
juice of 1/2 lemon
1 tablespoon cornstarch
1 tablespoon water
1 egg
1 tablespoon water
12 ounces wonton wrappers
1 tablespoon butter, melted
2 tablespoons butter
1 teaspoon cinnamon
3 tablespoons granulated sugar
1 cup heavy cream
Place the blueberries, brown sugar, and lemon juice in a pot. Heat over low heat, stirring occasionally, until the blueberries are thawed and begin to release their liquid, about 5 minutes.
Whisk the cornstarch and the water together, and slowly stir the slurry into the blueberries. Continue cooking until the filling thickens, an additional 3-4 minutes. Remove from the stovetop and set aside. Allow to cool completely.
Whisk the egg with a tablespoon of water. To assemble the pierogi, take a wonton wrapper and fill with about 2 teaspoons of the filling. Brush the edge with egg, and fold the pierogi into half-moons. Set aside on a baking sheet.
When all of the pierogi have been stuffed, brush them on one side with the butter. Combine the cinnamon and granulated sugar, and sprinkle over the tops of the pierogi.
Heat about a teaspoon of the remaining butter in a skillet, and arrange as many pierogi as you can, sugared-side down, in an even layer. Cook for about 2-3 minutes, then flip and continue cooking an additional 2-3 minutes. Set aside and continue with the next batch until all of the pierogi are cooked.
Add the heavy cream to the pan and reduce for about 2 minutes. Add the pierogi back to the pan and cook an additional 2 minutes, until heated through.