Preheat oven to 200 degrees. Make the pancakes: Whisk together flour, hazelnut meal, baking powder, and 1 teaspoon salt in a bowl. Whisk eggs in another bowl, then whisk in milk, sugar, and oil. Whisk egg mixture into flour mixture until just combined (with some lumps remaining). Heat a griddle or nonstick skillet over medium heat (or heat an electric griddle to 350 degrees).
Lightly oil griddle. Scoop 1/3 cup batter onto heated griddle. Cook until edges are dry and some small bubbles come to the surface, about 3 minutes. Flip, using a thin spatula. Cook until firm to the touch, about 3 minutes. Transfer to a baking sheet, and keep warm in oven. Repeat with remaining batter.
Make the raspberry sauce: Heat jam and water in a small saucepan over medium heat until warm and pourable, adding an additional tablespoon water if needed. Stir in lemon juice. Serve pancakes warm with butter and warm raspberry sauce.
Storage: Pancakes can be frozen for up to 1 month.