6 tablespoons unsalted butter
1/2 rounded cup slivered almonds
1/2 cup granulated sugar
3 egg whites
1/4 cup plus 2 tablespoons cake flour
2 teaspoons dark rum or 1 teaspoon vanilla extract
Heat butter in small saucepan over medium heat. Cook, swirling pan occasionally, until butter turns deep brown. Remove saucepan from heat immediately and set aside.
Whirl together almonds and sugar in food processor for 1 minutes or until ground. Transfer to clean saucepan. Stir in egg whites. Heat over very low heat, stirring, until mixture is hot to touch and "runny," about 2 minutes. Remove from heat. Stir in flour. Stir in the reserved butter and the rum or vanilla extract until blended. Cover with plastic wrap and chill one hour or up to three days before baking.
Preheat oven to 400 degrees F. Grease two mini-muffin tins. Fill each muffin cup with 1 1/2 teaspoons batter. Bake for 12 to 14 minutes, or until tops are crowned and golden. Pry cakes from tins with small knife. While still warm, brush lightly with orange marmalade, if desired. Cool on rack. Store in airtight container up to three days.
NOTE: Cakes can be made in standard-size muffin tins. Divide batter evenly among 12 greased muffin cups. Bake at 400 degrees F for 15 minutes.