Buttermilk Cake With Spiced Vanilla Icing

Ingredients

• 4 oz. (1/2 cup) unsalted butter, softened; more for the pan
• 13-1/2 oz. (3 cups) unbleached all-purpose flour; more for the pan
• 1-1/2 cups granulated sugar
• 1/2 cup canola oil
• 2 large eggs
• 1 tbs. distilled white vinegar
• 2 tsp. pure vanilla extract
• 1 tsp. baking soda
• 1 tsp. table salt
• 1/2 tsp. ground ginger
• 1/4 tsp. freshly grated nutmeg
• 3/4 cup buttermilk
• 2-1/4 cups peeled and grated butternut squash
• 9 oz. (2-1/4 cups) confectioners’ sugar
• 3 tbs. buttermilk; more as needed
• 1 tsp. pure vanilla extract
• 1/4 tsp. freshly grated nutmeg
• 1/4 tsp. table salt
• 1/4 cup finely chopped crystallized ginger