If you can’t find Meyer lemons (which you totally should because they are awesome), regular lemons will work.
This is, in essence, a deconstructed pie or tart. The crumble serves as the crust, so make sure there is a good ratio of crumble to custard so they get some crunch in every bite.
Feel free to serve these as little cute parfaits (alternating crumble and custard, and then topping with the honey mascarpone). You can also leave all three components out and let guests build their own (hello easy entertaining!).
When I serve this, I put it in the little mini flare serving dishes you see in the photos (they hold just under 3 ounces each). I get about 10 to 12 servings with them. The custard is quite rich, so small servings are totally acceptable.
Lemon Custard barely adapted from Thomas Keller’s Bouchon Cookbook.