Preheat oven to 350 degrees, with rack in top position. Line 18 muffin-pan cups with paper liners. In a large bowl, using an electric mixer, beat butter, sugar, and 1/3 cup marmalade until pale yellow and fluffy, 4 minutes. In a food processor, process almonds until finely ground. Add flour, baking powder, baking soda, and salt and process until almonds are completely incorporated into flour mixture.
With mixer on low, beat eggs, one at a time, into butter mixture, scraping down bowl after each addition. Add buttermilk and flour mixture each in three additions, scraping down bowl after each addition. Beat in vanilla.
Fill each muffin cup with cup batter. Bake until golden brown and a toothpick inserted in center of a cupcake comes out clean, 22 to 24 minutes, rotating pans halfway through. Let cupcakes cool in pans on wire racks. Top each with a dollop whipped cream and evenly drizzle with 1/3 cup marmalade.
Microwave your marmalade if it's too thick to pour. Heat for 5 to 10 seconds or until it loosens up.