Lightly spoon flour and masa into dry measuring cups; level with a knife. Combine flour, masa, sugar, salt, and yeast in a large bowl, stirring with a whisk. Add milk, butter, and 2 eggs; stir with a wooden spoon 1 minute or until smooth.
Spread dough into a 13 x 9-inch baking pan coated with cooking spray. Cover with plastic wrap, and let rise in a warm place (85°), free from drafts, 1 hour or until doubled in size.
Preheat oven to 375°.
Bake at 375° for 25 minutes or until bread is light golden brown and springs back when touched lightly in center. Cool in pan for 5 minutes before serving. Serve warm.