Set oven to 350 degrees Fahrenheit.
Prepare baking pan by spraying with oil and sprinkling flour to help prevent sticking.
Sift together the bread flour, cake flour, baking powder and baking soda into a large bowl.
Zest orange and add to bowl of flour
Add poppy seeds to bowl.
In a medium bowl, cream the butter and 3⁄4 cup of the sugar together.
Separate eggs and add egg yolks to the butter and sugar mixture. Add vanilla extract. Mix thoroughly.
Combine the butter mixture with half of the flour mixture until thoroughly blended.
Stir in the sour cream.
Blend in the remaining flour mixture.
Using a stand or hand mixer, whip the egg whites, salt, and cream of tarter on high until a foam is created. Slowly whip in remaining sugar until stiff peaks form.
Gently fold the egg white mixture into the cake batter. Do not overmix.
Spread the cake batter evenly around the cake pan.
Bake for 40 minutes or until cake tester comes out clean.
If making muffins, prepare muffin pans with oil spray and flour or use muffin cups. Bake at 375° for 25 minutes or until cake tester comes out clean.
Allow pan to sit out until completely cooled on a cooling rack. Use a knife gently run around the edges of the pan. Turn upside down just over the cooling rack and give it a hard shake to pop the cake out.
Top the cake with orange marmalade glaze.
Store in a covered container.