Heat the cream slightly and stir in the instant coffee until it has dissolved. Add the whiskey, stir well. Place paper liners in the muffin tin or grease them well. Preheat the oven to 180 ° C (center, convection 160 ° C).
Mix the flour, baking powder and cinnamon together. In a large bowl, beat the egg yolks, sugar, oil and salt until frothy. Sift the flour and cinnamon mixture into the egg yolk mixture in 4 steps. Mix well every time. Stir in the coffee cream and chopped walnuts. Pour the batter into the muffin pan.
Bake in the preheated oven for about 20-25 minutes. Let rest in the baking tray for 5 minutes, then remove from the tin and place on a wire rack to cool.