Pre-heat oven to 300°F;
In the bowl of an electric mixer, cream together the butter and sugar; thoroughly combine.
Add the eggs, one at a time, beating well after each addition, until light and fluffy.
Beat in the vanilla and lemon zest.
In a medium bowl. sift together the flour and baking powder.
Fold dry ingredients into the creamed mixture, alternating with the evaporated milk, beginning and ending with the dry ingredients; as a general rule, add the dry ingredients in 3 portions and the milk in 2 portions.
Fold in the baking gums that have been tossed at the last minute in the ¼ cup flour.
Bake in a greased and floured bundt pan or in a spring form pan, tube pan, or two 9 x 5-inch loaf pans lightly greased and lined with parchment paper.
Bake in pre-heated oven for 1 and 45 minutes depending upon the size of your pan; since small loaf pans may be done just under an hour, test the smaller pans after 50 minutes.
Baking times vary greatly on this recipe so rely on the toothpick test to ensure that it is properly baked; when a wooden toothpick, inserted in the center, comes out clean, its done.
Be careful not to go past this stage or the cake will be dry.
Let the cake cool in the pan/s for 10 minutes before turning it out onto a wire rack to cool completely.