Preheat oven to 400°F.Arrange the brioche slices on half sheet pans, leaving just a little room between the pieces.Heat the Nutella and raspberry preserves or jam together in a saucepan over very low heat or in a microwave safe bowl in 10 second bursts, stirring after each one, until loose and hot. Stir well until evenly combined.
Divide the Nutella and preserve mixture evenly between the slices of brioche. Spread them evenly over the bread to the edges and let it soak into the bread while you prepare the Frangipane.Use a sturdy spoon, hand mixer, or stand mixer to mix together the almond meal, butter, sugar, eggs, extracts, and pinch of salt until it forms a cohesive, smooth paste. Divide the mixture evenly between the slices of brioche, using a butterknife to spread it evenly to the edges.
Sprinkle the almonds over the frangipane then bake until the tops are set and puffy and golden brown, about 16-24 minutes. Dust generously with powdered sugar and serve warm or room temperature.Leftovers can be stored wrapped or in a loosely covered container at room temperature for 3 days. See Cook's Notes for instructions on refreshing or reheating.