To make lemon pudding bundt cake, whisk 1 3/4 cups flour, 3 tablespoons cornstarch, 4 teaspoons baking powder and 1 teaspoon salt together in a bowl. In the bowl of an electric mixer, cream 3/4 cup softened unsalted butter with 1 1/2 cups granulated sugar.
Cream the butter and sugar together, add 1 package of lemon pie filling mix, and mix it thoroughly into the butter mixture. Add 4 eggs, one at a time, beating them until each is fully combined in the butter mixture before stirring in 2 tablespoons of fresh lemon zest. Pour 1 1/4 cup whole milk in a large measuring cup. Add 1/3 cup canola oil and 1 teaspoon vanilla extract to the milk, and whisk it to combine the three ingredients.
Alternate adding the dry and wet ingredients to the butter mixture, starting with the flour and adding one-third of each at a time. After the final addition, mix the batter for two minutes at medium speed. Pour the batter into a greased and floured bundt pan. Bake it for 50 to 60 minutes at 325 degrees Fahrenheit.
Alternatively, combine 1 box of lemon cake mix with 1 package instant lemon pudding mix, 4 eggs, 1 cup water and 1/3 cup oil. Beat the mixture for two minutes before pouring it into a prepared bundt pan. Bake it for 35 to 40 minutes at 350 F.