1/3 cup coarsely chopped walnuts, toasted (about 1 1/3 ounces)
Icing
1 1/2 cups confectioners’ sugar
3 tablespoons cold black coffee
1 tablespoon coffee liqueur (optional)
1/2 teaspoon ground cinnamon
Recipe
1. Preheat oven to 350° F. Grease 12 standard size muffin-pan cups or line with paper liners. Dust with flour; tap out excess.
2. To prepare caramel, in a small, heavy saucepan, bring sugar and lemon juice to a boil over medium heat. When mixture begins to brown around edges, reduce heat to low. Cook without stirring until mixture turns a deep golden color.
3. Carefully add boiling water all at once to caramel. Bring caramel mixture to a boil. Remove from heat. Cool for 20 minutes.
4. To prepare cupcakes, mix together flour, baking powder, and salt. Beat together butter and brown sugar at medium speed until light and fluffy. Beat in egg, egg yolk, and vanilla.
5. At low speed, alternately beat flour mixture, caramel, and sour cream into egg mixture until well blended. Stir in nuts. Spoon batter into prepared pan, filling cups three-quarters full.
6. Bake cupcakes until tops are firm, 20 minutes. Transfer pan to a wire rack to cool slightly. Turn cupcakes out onto rack to cool completely.
7. To prepare icing, mix together confectioners’ sugar, coffee, coffee liqueur, and cinnamon until well blended. Spread icing evenly over cupcakes. Let stand until icing has set.