Preheat the oven to 375°F. Put the flour, brown sugar, salt, and baking powder in the food processor, and pulse to combine. Add the butter and process while you count to 20. (The mixture shouldn't have any chunks of butter.)

Dump the flour mixture into a mixing bowl. Add the oats, coconut or walnuts, and stir to combine. Press about 3/4 of the mixture into the bottom of the baking dish. Really mash it hard with clean hands.

Spread the raspberry jam in an even layer on top of the crust. Sprinkle the rest if the crumb mixture in top if the jam.

Bake 35 to 40 minutes, until the top is browned. Use oven mitts to remove the baking dish from the oven. Let the dessert cool to room temperature before cutting into triangles. Enjoy!