Preheat the Oven: Preheat your oven to 350°F (175°C). Grease and flour a cake pan.
Mix Wet Ingredients: In a large bowl, cream together the softened butter and granulated sugar until light and fluffy. Add the egg whites, canola oil, milk, and vanilla extract. Mix until well combined.
Combine Dry Ingredients: In another bowl, whisk together the all-purpose flour, baking powder, and salt.
Combine Mixtures: Gradually add the dry ingredients to the wet mixture, mixing until just combined. Fold in the sprinkles gently.
Bake: Pour the batter into the prepared cake pan and bake for about 25-30 minutes, or until a toothpick inserted into the center comes out clean. Let cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.
Make the Frosting: In a bowl, beat together the softened butter and double cream until creamy. Gradually add the powdered sugar and vanilla, mixing until smooth and fluffy.
Frost the Cake: Once the cake is completely cool, spread the frosting evenly over the top and sides of the cake. Decorate with additional sprinkles.
Serve: Slice the cake and enjoy your delicious vanilla cake with sprinkles!