Put the speculoos into a freezer bag and crumble finely with the cake roll. Knead with butter. Spread the biscuit-butter crumbs evenly on 6 tartlet cups (10 cm Ø) with lift-off base and press them down to a smooth base and edge. Chill for about 30 minutes.
Wash a lemon, grate dry and finely grate the peel and cut off 6 very thin, beautiful slices from the middle. Halve the remaining 2 lemons and squeeze them
Beat the eggs, egg yolks, condensed milk, lemon peel and lemon juice with the whisk of the hand mixer. Pour into the moulds, place a slice of lemon on each and bake in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for 15-20 minutes. Leave to cool and chill for at least 2 hours.
waiting time approx. 2 hours