Lemon Mascarpone Stuffed Ebelskivers (Danish Pancakes) With Blueberry Thyme Compote

To make the blueberry thyme compote, heat the blueberries, sugar, lemon juice, lemon zest, and thyme in a medium saucepan over medium low heat. Cook until blueberries burst and release their juices, about 6 minutes. Set aside.
To make the ebelskiver batter, whisk the flour, baking powder, baking soda, 2 tablespoons sugar, salt, and 1 teaspoon lemon zest together in a bowl. In a separate bowl, whisk the egg yolks and buttermilk together. Pour the liquid into the dry ingredients and stir until combined. The batter will be lumpy. In a separate bowl, beat the egg whites until stiff peaks form. Fold them into the batter.
To make the lemon mascarpone filling, mix the mascarpone cheese, lemon juice, 3 teaspoons lemon zest, and 1 tablespoon sugar together in a bowl. Set aside.
Heat the ebelskiver pan over medium heat. Brush each of the wells with melted butter. Fill each well about halfway with the batter. Gently place a small dollop (approximately 3/4 teaspoon) of the lemon mascarpone filling in the center of each pancake, and top with more batter to cover the filling. Cook until bubbles start to form around the edges of the pancakes and the bottoms are golden brown. Flip the pancakes over with the ebelskiver wooden flipping sticks or two teaspoons, and cook on the second side until golden brown. Remove and plate. Serve ebelskivers with blueberry thyme compote.