Grind @speculoos{150%g}, add @butter{80%g} and @sugar{60%g}. 
Press into the bottom of jars (about 1-2 cm thick). 
Bake at 140°C for ~{10%min}. Let cool for ~{15%min}.
Put @cream cheese{120%g}, @sugar{60%g}, and @cornstarch{2%tbsp} in a #mixer{} with a paddle attachment and beat on low speed until creamy, about ~{5%min}. 
Blend in remaining @cream cheese{330%g}.
Increase mixer speed to medium, add remaining @sugar{110%g} and a pinch of @vanilla. 
Add @egg{1%large}, beating well. Add @heavy cream{170%g} and mix briefly until just combined (do not overmix!).
Pour about 170ml of batter into each jar (enough for about 7 jars). 
Place jars in a #water bath{} set to ~{80°C}, and once it reaches temperature, set a timer for ~{90%min}. 
After, remove jars and let cool to room temperature before placing in the #fridge{}.