In a stand mixer fitted with the whisk attachment (or use a hand held mixer), beat egg whites until they start to bubble. Sprinkle in 1 tablespoon of the sugar; continue beating until soft peaks form. Set aside.
In a separate larger mixing bowl, combine the ricotta, buttermilk, 3 egg yolks, melted butter, vanilla and lemon zest. Next add the flour, baking soda and salt, stirring gently until just combined.
Stir a small scoop of the egg whites into the ricotta pancake batter to lighten the batter, then fold in the remaining whites with a spatula.
Heat a skillet on medium heat. Grease with butter or cooking spray. Pour 1/3 cup pancake batter on the center of the hot pan. Sprinkle each pancake with chocolate chips. Cook until bubbles appear on the surface. Using a spatula, gently flip the pancake over and cook the other side for a minute, or until golden. Repeat with the remaining batter.
To serve, top each pancake with a little whipped mascarpone and a large spoonful of the warm roasted rhubarb. Finish with a drizzle of honey. EAT!