Whirl hazelnuts in a food processor until finely ground. Add cornmeal and whirl to combine. Add flour, sugar, baking powder, and salt and whirl to combine. Add eggs, milk, and butter. Pulse to just combine with dry ingredients.
Drop batter in 3-tablespoon portions onto a frying pan over medium-high heat. Turn pancakes when bubbles appear on the surface, cooking about 3 minutes total per pancake.
Toasting nuts: Toasting nuts makes them crunchier and intensifies their flavor. In the case of thin-skinned nuts like hazelnuts or peanuts, it also makes removing their skins easier.
To toast a small amount: Place nuts in a small frying pan over medium-high heat and cook, stirring frequently, until they smell fragrant and turn a light shade of golden brown (they will continue to toast a bit more when removed from heat).
To toast larger batches: Spread the nuts in a single layer in a shallow baking pan and toast in a 375° oven for 10 to 15 minutes until the nuts are lightly browned and smell rich and toasty.
To skin nuts after toasting: Place them in a kitchen towel and rub vigorously. Most of the skins will fall right off. Don't worry if a few bits still cling here and there; they won't harm the flavor or texture.
Note: Nutritional analysis is per pancake.