Cheese puff sliders

Put sliced butter, a big pinch of salt and cold water in a saucepan over medium-high until the butter melts and the water simmers at the same time.

Reduce to medium, add the flour all at once and stir with a wooden spoon until a smooth pasty dough forms, a minute or two; lumps at first are normal.

Keep cooking at least another minute to cook the flour and dry the mixture, scraping the film off the bottom.

Turn off the heat and keep stirring and scraping about a minute; the dough's moisture deglazes the pan.

Transfer to a bowl, season with cayenne and black pepper, and beat in the first egg until the dough comes back together and turns sticky, then the second.

Scrape the spoon and bowl; the dough is right when it forms a pointed tip on the spatula (a clump is too thick, dripping too thin).

Fold in grated Gruyere and sharp cheddar.

Scoop 12 equal portions onto a Silpat-lined baking sheet; add leftover dough to the small ones and neaten with wet fingers.

Using a ring cutter as a guide, top each with a rounded tablespoon of grated cheese; push stray shreds against the base.

Put into the center of a 450F oven, immediately turn down to 375F and bake about 35 minutes until puffed and golden brown.

Rest on the pan three or four minutes, then cool on a rack.

Pan-fry the small beef patties over medium-high without moving them until crusted, a few minutes; flip and cook a couple of minutes more; season both sides with salt and pepper.

Done when they spring back and juice leaks out; rest on a plate a few minutes.

Cut a cheese puff like a bun; dress with secret sauce of two parts mayonnaise to one part mustard and one part ketchup.

Add the patty, a slice of bread and butter pickle and sliced cherry tomato, and close.