To prepare muffins, weigh or spoon 5 ounces spelt flour and whole-
wheat pastry flour into dry measuring cups. level with a knife.
Combine flours, cinnamon, baking powder, baking soda, and salt in
a medium bowl.
Combine buttermilk, 1/2 cup sugar, oil, 1 tablespoon melted
butter, and egg in a bowl. Add buttermilk mixture to flour mixture,
stirring just until combined. Fold in apple. Divide batter among 12
paper-lined muffin cups; top evenly with streusel. Bake at 400 for
16 minutes or until a wooden pick inserted in the center comes out
with moist crumbs clinging. Cool in pan 5 minutes. Remove from
pan and cool completely.