Preheat oven to 350°F (177°C). Grease a 9×5-inch loaf pan.

In a large bowl, whisk together cake flour, baking powder, baking soda, and salt.

In a separate bowl, whisk melted butter, egg, sugar, sour cream, milk, and vanilla extract until smooth.

Add wet ingredients to dry ingredients and whisk until just combined. Do not overmix.

Fold in the sprinkles.

Pour batter into prepared pan and bake for 50–60 minutes. Cover loosely with foil halfway through baking if the top browns too quickly.

Test for doneness with a toothpick inserted into the center. If it comes out clean, remove from oven.

Cool completely in the pan on a wire rack.

Remove the cooled cake and carefully slice it horizontally into three even layers.

Allow the ice cream to soften for about 15 minutes.

Line the loaf pan with parchment paper or plastic wrap, leaving overhang on the sides.

Place the bottom cake layer into the lined pan.

Spread one pint of softened ice cream evenly over the cake layer.

Add the middle cake layer and spread the remaining pint of ice cream on top.

Place the final cake layer on top and gently press down.

Cover and freeze the assembled Ice Cream Loaf Cake for at least 8 hours.

For the ganache, place chopped chocolate in a heatproof bowl.

Heat cream until gently simmering and pour over chocolate.

Let sit for 2–3 minutes, then stir until smooth.

Allow ganache to thicken slightly for about 10 minutes.

Remove cake from freezer and carefully lift from the pan.

Pour ganache over the top and garnish with sprinkles if desired.

Let stand for 3–5 minutes before slicing.

Slice with a sharp serrated knife and serve.