Whisk eggs, half-and-half, and hazelnut liqueur together in a shallow bowl.

Melt 1 teaspoon butter in a large skillet, tilting the skillet to assure complete coverage.

Dip 2 slices brioche in the egg mixture, moistening both sides.

Cook brioche in the hot skillet until golden brown, 2 to 4 minutes per side. Repeat process until all bread is cooked.

Cut each slice of brioche into half on a bias. Sprinkle hazelnuts over the halves and top with maple syrup.