11. Sweet Potato–Chocolate: Make Banana Muffins (No. 9), replacing the nuts with mini chocolate chips and the banana with canned sweet potato purée.
12. Pumpkin: Make Banana Muffins (No. 9), adding 1 teaspoon pumpkin pie spice with the flour, omitting the nuts and replacing the banana with canned pure pumpkin. Top with hulled pumpkin seeds and turbinado sugar before baking.
13. Persimmon: Make Banana Muffins (No. 9), adding 1/2 teaspoon cinnamon and 1/4 teaspoon ground cardamom with the flour, omitting the nuts and replacing the banana with 3/4 cup puréed, peeled persimmons.
14. Chocolate: Melt 6 tablespoons butter with 1/2 cup chopped bittersweet chocolate. Mix 1 3/4 cups flour, 3/4 cup sugar, 1/2 cup cocoa powder, 1 teaspoon baking powder, 1/2 teaspoon salt and 1/4 teaspoon baking soda. Whisk 1 cup milk, 1 egg and 1 teaspoon vanilla, then stir into the flour mixture. Stir in the melted chocolate mixture. Divide among 12 prepared muffin cups and bake 22 to 28 minutes.
15. Cherry-Chocolate: Thaw, drain and chop 1 cup frozen pitted cherries. Make Chocolate Muffins (No. 14), adding the cherries with the flour and 1/4 teaspoon almond extract with the vanilla.
16. Chocolate Macaroon: Mix 1 1/2 cups shredded coconut, 1 beaten egg white, 2 tablespoons sugar and 1/4 teaspoon vanilla. Make Chocolate Muffins (No. 14), filling the cups halfway with the batter; top with the coconut mixture and the remaining batter, then bake.
17. Candy Cane: Make Chocolate Muffins (No. 14), adding 1/4 cup crushed peppermint candies with the flour. Sprinkle with more crushed candies before baking.
18. Blueberry-Corn Tops: Make Corn Muffins (No. 23), replacing the regular flour with cake flour and adding 3/4 cup blueberries with the flour; increase the sugar by 2 tablespoons and the baking powder by 1 teaspoon, and reduce the milk to 1/3-2/3 cup. Arrange 1/3-cup mounds of batter 2 inches apart on oiled baking sheets. Chill 30 minutes, then bake at 375 degrees F, 16 to 18 minutes.
19. Mexican Hot Cocoa: Make Chocolate Muffins (No. 14), adding 1 teaspoon cinnamon with the flour. Bake and cool, then insert a cinnamon stick into each and top with halved mini marshmallows.
20. Chocolate-Pecan Pie: Make Chocolate Muffins (No. 14). Make a dent in each while still warm; cool. Cook 1/4 cup each brown sugar, corn syrup and butter with 1 beaten egg and 1 teaspoon each cornstarch and vanilla over medium heat, stirring, until thick. Stir in 3/4 cup chopped pecans; cool. Spoon the pecan mixture over the muffins.