Preheat oven to 425°F and place a rack in the center. Lightly spray two 6 ring donuts pans with nonstick spray.
In a large mixing bowl, sift together all of the dry ingredients and whisk to combine.
In a medium bowl whip the heavy cream until soft peaks form. Add the whipped cream, beaten eggs, oil, water and vanilla to the dry ingredients and stir together with a spatula just until combined.
Divide the batter between 12 donut cups (each portion takes about 60 grams of batter). Pipe the batter into the pans for more control.
Tap the pans on the counter 3-4 times. Bake pans side by side in the center of the oven for 9-11 minutes or until a toothpick comes out with moist crumbs.
Cool the donuts in the pan for 5 minutes then turn onto a rack and cover with a clean tea towel to cool completely, about 30 minutes.
Make the glaze by combining the melted butter, hot water, vanilla and salt in a cereal bowl with a whisk. Add the powdered sugar and whisk until smooth, adding a few drops of water to adjust the consistency to a dippable texture.
Dip the tops of the donuts and immediately add sprinkles. Store leftovers in an airtight container for 2 days.
