Melt the butter. Crumble the shortbread (see tip below). Knead melted butter and shortbread crumbs. Line a tray with baking paper. Place a dessert ring (approx. 8 cm Ø) on the baking paper.
Add approx. 1⁄6 of the crumb mass and press it to the flat bottom. Remove the ring carefully. Make 5 more bases from the remaining crumb mass in the same way. Put all bottoms in a cold place.
Preheat oven (electric cooker: 150 °C/circulating air: 125 °C/gas: see manufacturer). Coat the troughs of the muffin tin with oil, place the tin on a fat pan of the oven. Mix cream cheese and lemon curd.
Whip 100 g cream until stiff, fold in. Beat the egg whites until stiff, then add 2 tablespoons of sugar. Carefully fold into the cream cheese mixture in 2 portions. Fill the cream into the hollows.
Push the fat pan into the hot oven. Pour so much hot water on it that the muffin tin for approx. 2⁄3 is in the water. Bake for about 20 minutes. Turn off the oven, open the oven door and let the tartlets cool down in the oven for about 30 minutes.
Remove the fat pan from the oven and lift out the muffin tin.
Place the shortbread bases on the tartlets and press down lightly. Cover the muffin tin with cling film and freeze for about 1 hour.
Carefully press the tartlets out of the moulds and let them thaw in a cool place for about 30 minutes. Wash lime hot, grate dry and cut into 6 slices. Whip 150 g cream until stiff and fill into a piping bag with a large perforated spout.
Spray as tuffs on the tartlets and decorate with lime.