Preheat your oven to 350°F (175°C). Grease a 9x5 inch loaf pan and line it with parchment paper, leaving an overhang on the long sides.
In a medium bowl, whisk together the gluten free baking flour, almond flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, beat the softened butter and granulated sugar with an electric mixer until light and very fluffy, about 4 minutes. Beat in the eggs one at a time, then mix in the vanilla extract, almond extract, sour cream, and milk until completely smooth.
Fold the dry ingredients into the wet mixture using a spatula until just combined. Gently fold in the 1/2 cup of rainbow sprinkles and the white chocolate chips, being careful not to overmix or the sprinkles will bleed color.
Pour the batter into the prepared pan and smooth the top. Scatter the remaining 2 tablespoons of sprinkles over the surface.
Bake for 50 to 58 minutes, until the bread is golden on top and a toothpick inserted in the center comes out clean or with a few moist crumbs. If the top browns too fast, tent it loosely with foil after 35 minutes.
Let the bread cool in the pan for 15 minutes, then lift it out using the parchment paper and cool on a wire rack. The inside will be soft, buttery, and cake-like with pockets of melted white chocolate and pops of color throughout.