Crush the speculoos cookies using a pestle or mixer until you achieve a fine powder. Mix thoroughly with the melted butter. Pour the mixture into the mold and press it down firmly with the bottom of a glass. Place in the freezer for a few minutes to set.

Preheat the oven to 180 °C (350 °F). Zest the lemon. Beat the cream cheese for 30 seconds using a mixer (or whisk) until smooth. Add the ingredients one by one, briefly mixing after each addition: sugar, flour, lemon zest, vanilla powder, followed by the eggs and yolk (one at a time). Finally, add the crème fraîche and mix just enough to incorporate.