1 cup freshly squeezed satsuma juice
or orange juice
1/2 cup sugar
1 tsp. satsuma zest or orange zest
3 tbsp. Grand Marnier
1 tbsp. cornstarch
4 tbsp. unsalted butter, cut into cubes
1/4 cup orange marmalade
1. Combine juice, sugar, and zest in a 1-qt. saucepan and stir until dissolved over high heat, about 3 minutes.
2. Meanwhile, combine Grand Marnier and cornstarch in a small bowl and stir to dissolve. Add the cornstarch mixture to the saucepan. Bring sauce to a boil and cook, stirring occasionally, until sauce thickens, 5 minutes.
3. Remove from heat and whisk in butter and marmalade. Let cool to room temperature before drizzling over cake.
MAKES 1 3/4 CUPS