Preheat the broiler and position an oven rack 8 inches from the heat
Prepare asparagus by holding asparagus spear in your hand and breaking off the bottom where it snaps; this is the tough part of the stem Discard
Melt butter in a large saut pan Add minced shallots and cook over moderately high heat until softened about 1 minute Add prepared asparagus season with salt and pepper and cook briefly over moderate heat stirring occasionally until crisp-tender
Transfer asparagus to a medium gratin dish and arrange with asparagus heads pointing in once direction
Combine crme fraiche and grated gruyere cheese Spread evenly over asparagus When ready to serve broil until golden and bubbling shifting the dish for even browning about 1-3 minutes Sprinkle with tarragon and serve
