2 1/4 cups vegetable shortening
6 tablespoons. 3/4 stick, unsalted butter
1 1/2 tablespoons pure vanilla extract
1/4 cup plus 2 tablespoons cold water
Put the sugar, shortening, butter, and vanilla in the bowl of a stand mixer fitted with the paddle attachment and paddle at low-medium speed until the mixture is smooth, with no lumps, about 3 minutes.
With the motor running, add the water in a thin stream and continue to paddle until absorbed, about 3 minutes.
The buttercream can be refrigerated in an airtight container for up to 2 weeks.