Vanadium

Cupcakes
1/2 cup (114 g) unsalted butter softened
1/2 cup (120 ml) canola or grapeseed oil
1 3/4 cups (345 g) sugar
1 teaspoon vanilla extract
1 teaspoon baking soda
1/2 teaspoon baking powder
1/2 teaspoon salt
2 large eggs
1/2 cup (113g) full fat sour cream
1/4 cup mayonnaise
2 1/2 cups (300 g) all-purpose Flour
3/4 cup unsweet cocoa powder 
3 cups shredded organic zucchini (about 3 medium)

Dark chocolate buttercream
1 cup (228 g) unsalted butter, softened
1/4 teaspoon salt
4 cups (455 g) confectioners’ sugar
1/2 cup (45 g) unsweet cocoa powder
6 ounces dark chocolate, melted
Heavy cream, as needed

Preheat the oven to 325°F. Line two cupcake pans with paper liners (makes 24 cupcakes). 

Make the cupcakes: In the bowl of an electric mixer, combine the butter, oil, sugar, vanilla, baking soda, baking powder and salt. Beat in the eggs one at a time.

Add the sour cream, mayonnaise and cocoa powder. Stir in the flour. Beat until well combined. Fold in the zucchini with a rubber spatula. 

Spoon the batter into the cupcake papers 3/4 full. Bake for 20-25 minutes, or until a toothpick tester comes out with a few moist crumbs clinging to it. The cupcakes will puff in the oven as they bake, but will sink slightly when removed from the oven (expect this). Remove the cupcakes from the pan and cool on a wire rack. Cool completely before frosting.

Make the frosting: In the bowl of an electric mixer with the whip attachment, beat together the butter and salt. Add the confectioners’ sugar and cocoa powder. Mix on low speed until just combined (the mixture may be crumbly at first – keep mixing!). Add the dark chocolate frosting and whip on high speed. Add heavy cream a little at a time until the mixture is piping consistency. You may need 1/4 cup or more depending on the cornstarch content of your confectioners’ sugar. Scrape down the bowl and whip again until light and fluffy.

Transfer the frosting to a piping bag fitted with a large French tip. Pipe the frosting onto the cupcakes.