Start by preheating your oven to 300 F then liberally grease and flour a tube pan, bundt pan, large loaf pan or two smaller loaf pans or you can use non stick baking spray or my cake release recipe.
In your stand mixer bowl, add butter, shortening and sugar and mix for 4-5 minutes on high speed until very pale yellow, creamy and fluffy.
Next add eggs, one at a time, combining well after each addition and scraping down the sides of your bowl as needed.
While eggs are going, sift together dry ingredients (flour and baking powder).
Turn your mixer down to its lowest speed, and slowly alternate the dry ingredients with the sour cream, milk, vanilla and lemon extract.
Pour batter into greased pan or pans. Bake in oven for 1 hour and 30 minutes for 1 vessel and start checking around 45 minutes for 2 small vessels. Or until a toothpick inserted in the center of the cake comes out clean.
Cool in pan on a wire rack for 10 minutes then invert cake on serving plate for at least an hour or until the cake is cool to touch.