Preheat the oven to 350 degrees F., Spray a 10 to 12 cup bundt pan with nonstick spray.
In a medium bowl, whisk together flour, baking powder, baking soda and salt.
In a large bowl, use an electric mixer to combine the sugar, butter and oil at medium speed for 4 minutes or until light and fluffy. Beat in whole eggs, one at a time. Beat in the vanilla.
At low speed, beat in the flour mixture and buttermilk, making three additions of flour and two of buttermilk, and beating until incorporated.
In another medium glass or stainless steel bowl, using the handheld mixer and clean beaters, beat the egg whites on medium-low speed until foamy. Gradually increase to high speed and beat until firm peaks form.
Using a spatula, carefully fold whites into batter in two additions. Fold in the sprinkles (see Recipe Notes below). Transfer the batter to the prepared pan and smooth the top.
Bake in a preheated oven for 45 to 55 minutes or until a tester inserted in the center comes out clean. Let cool in pan for 10 minutes, then carefully invert the cake onto a wire rack to cool completely.
PREPARE THE GLAZE:
In a small saucepan, stir together the white chocolate, cream and salt over medium-low heat until melted and smooth. Whisk in 1 cup of the sugar. Whisk in more sugar, if necessary, 2 tablespoons at a time, until the glaze is thick but pourable.
Pour the glaze over the cooled cake, letting it drip down the sides. Decorate with plenty more sprinkles. Let the glaze set for at least 20 minutes before serving.
Notes
Don't use nonpareil sprinkles, which are the colored tiny round variety Use the sprinkle variety shaped like short cylinders, sometimes called "jimmies." Fold sprinkles gently into the batter to avoid coloring the batter.