To make the Raspberry Mint Mug Cakes, first place the raspberries in a colander, rinse and drain. Place on paper towels and carefully pat dry.
Place the egg in a mixing bowl with the sugar, vanilla sugar and salt. Beat with a hand mixer until thick and fluffy and the mixture is light yellow. Add the canola oil and stir it in. Sift the flour into the mixture and stir briefly. Finally, fold in the raspberries and mint leaves.
Grease two cups with butter. Divide the batter between the cups and microwave them one at a time at 800 watts for 1:55 minutes. Remove and while still hot, drizzle each with 1 tsp raspberry liqueur. Let cool and serve dusted with powdered sugar.
If preparing without microwave, use oven-proof cups. Preheat the oven to 180 °C and bake the raspberry mint mug cakes on the middle rack for about 25 minutes.