Preheat the oven to 400 degrees F.
Butter a nonstick mini-muffin tin with 12 (1/8-cup) wells that measure 1 3/4 inches in diameter and 3/4-inch deep. Mix 1 tablespoon of the flour with 1/2 the pine nuts in a small bowl. Dust the tins with the flour and nut mixture. Tap out the excess.
Melt the 1 tablespoon butter in a small saucepan over medium-high heat. Stir in the remaining 1 1/2 tablespoons flour and the jalapeno. Cook, stirring, for about 2 minutes. Whisk in the milk and add the cheese, salt, pepper, mustard, and egg yolk. Cool to room temperature.
Beat the egg white until firm but not stiff. Stir a 1/4 of the white into the cheese sauce. Gently fold in the remaining white. Spoon into the prepared tins, sprinkle with the remaining pine nuts, and bake until puffed and golden, 7 to 10 minutes. Cool in the tins on wire racks. When cool, run a small knife around the edge of each souffle. (The souffles will fall as they cool.) They can be prepared up to a day in advance and refrigerated. Bake in the muffin tins in a preheated 400 degree F oven for 5 to 7 minutes before serving.
One night on "Cooking Live" when I was removing the seeds and ribs from a jalapeno without the protection of surgical gloves, a viewer called in to say that at least I could make my job easier by using a grapefruit spoon. If you happen to have one kicking around the house, try it. It works nicely.
Recipe courtesy of Sara Moulton Sara Moulton Cooks at Home, Broadway Books, 2002