For the spiced butter: Put the butter in a small bowl. Add the agave, cinnamon, ginger and nutmeg and mash with a spoon until smooth. Transfer to a ramekin.
For the raspberry sauce: Add the jam and lemon juice to a small skillet and cook over low heat until melted and bubbling around the edges, 1 to 2 minutes. Keep warm or reheat before serving.
For the French toast: Combine 3/4 cup of the toasted coconut, the coconut milk, agave, millet flour, cinnamon, ginger, nutmeg, salt and banana in a blender. Blend on high until very smooth. Pour into a baking dish.
Heat a large nonstick skillet or griddle over medium heat. Brush with oil. Soak the challah in the batter, 15 to 30 seconds per side (to wet it, but don't saturate it). Add to the skillet and cook until caramelized on the bottom, about 2 minutes. Flip and cook the second side, about 2 minutes more.
Serve the French toast with the spiced butter and raspberry sauce, garnish with fresh raspberries and the remaining 1/4 cup toasted coconut.