Substitute for buttermilk in this recipe?

Hello! I don't have buttermilk, but have almond milk and heavy cream. Is it possible in this particular recipe to substitute it for one of these?

½ cup unsalted butter, room temperature 2 tsp. lemon zest or more — zest from 1 large lemon 7/8 cup* + 1 tablespoon sugar** 1 egg, room temperature 1 tsp. vanilla 2 cups flour (set aside 1/4 cup of this to toss with the blueberries) 2 tsp. baking powder 1 tsp. kosher salt 2 cups fresh blueberries ½ cup buttermilk***

• 7/8 cup = 3/4 cup + 2 tablespoons

http://ift.tt/GVsIs0

bon appetit