Preheat a nonstick griddle or large skillet. Combine flour, baking powder, nutmeg, salt, and sugar in a small bowl. Whisk together the cheese, eggs, milk, lemon juice and zest in a large bowl. Whisk the flour mixture into the wet ingredients until just combined. Brush the hot griddle with butter. For each pancake, pour approximately 1/4 cup measure of the batter on the griddle and cook, 3-4 minutes per side, until light golden brown. While the pancakes are cooking whip remaining ricotta with lemon zest. To serve, stack pancakes on a plate. Top with 2 -3 slices lox and a dollop of whipped ricotta cheese. Serve immediately.