Preheat oven to 350°F.
Lightly grease two 8x4-inch loaf pans.
In a large bowl, beat 1/2 cup softened butter with an electric mixer until creamy. Gradually add 1 1/3 cups sugar, beating well.
Add 4 large eggs to the butter mixture one at a time, beating after each addition and scraping down the sides of the bowl when about halfway through adding the eggs.
In a small bowl, stir together 2 cups mashed very ripe bananas, 1/4 cup heavy cream, 2 teaspoons vanilla extract, and 2 teaspoons lemon juice, then stir in 3/4 teaspoon almond extract.
In another bowl, whisk together 3 cups all-purpose flour, 2 teaspoons baking powder, 1 teaspoon baking soda, 1 teaspoon salt, and 1 teaspoon ground cinnamon.
With the mixer on low, add half of the flour mixture to the butter mixture. Add all of the banana mixture, then add the remaining flour mixture. Beat just until evenly combined. Stir in 1 cup white chocolate morsels.
Divide the batter between the prepared pans and smooth the tops. Bake 50 to 60 minutes, or until a wooden pick inserted in the center comes out clean.
Cool the loaves in the pans for 10 minutes, then transfer to a wire rack and cool completely.
Make the custard: in a medium bowl, whisk together 4 large eggs, 1 1/2 teaspoons vanilla extract, 3/4 teaspoon ground cinnamon, 1/2 teaspoon ground nutmeg, and 1 cup half-and-half until smooth.
When the loaves are completely cooled, cut one loaf into 9 slices.
Heat a griddle or large nonstick pan over medium-high heat.
Pour the custard into a shallow dish. Working in batches of three slices, add the slices to the custard, let sit 30 seconds, then flip and let sit another 30 seconds to coat both sides. Lift the slices and let excess custard drip back into the dish.
For each batch, melt 1 tablespoon butter in the hot pan, add the three custard-coated slices, and cook until lightly browned on the first side (about 2 minutes). Flip and cook the second side about 2 minutes, until golden. Repeat with the remaining slices, melting 1 tablespoon butter before each batch.
Serve the white chocolate banana bread French toast with maple syrup and whipped cream.