I make a cookie-nut crust for my cheesecakes. I don’t know how what I make for a 9” cheesecake translates to what is needed for your mini tarts (quantity-wise), but this is my recipe and how I bake and unmold it:
1 1/2 cups cookie/nuts
3 tablespoons melted butter
First, I generously butter my cake pan on the bottom and sides. Then I insert a 9” parchment round and butter that well, too. Next, I melt the butter and add it to the crumbs, and I mix those until the butter is well incorporated and all the crumbs have absorbed butter. I then press the crumb/butter mix into the bottom of the pan and use the bottom of a measuring cup to smooth and press it firmly. I bake this crust in a 350F oven for 10 minutes, then remove and cool it on a rack.
After I make my batter, I pour it into the cooled crust and bake. Then I remove the cake and cool it on a rack, followed by an overnight stay in the refrigerator.
When I want to unmold it, I set the cold cake on a range burner for about 15 seconds to melt the butter I lined the pan with in the first step. I heat a knife under hot water and run that around the edge of the cake, too. Another method is to dip the pan carefully in a pan of hot water. The whole idea is to melt the butter so the cake releases.
Finally, I place a cake round over the top of the pan, invert the pan and let it drop firmly from a couple of inches above the counter. If done right, the cake should slide out from the pan onto the cake round, after which I turn it right-side-up.
Hopefully, some of this will help you.