Step 1 Bring a large pot of generously salted water to a rolling boil. Cut off about 2 inches of the tips of 18 of the best-looking spears of asparagus and blanch 1 minute. Remove with a slotted spoon and plunge immediately into a bowl of ice water. Drain, pat dry and set aside.
Step 2 Break off the tough bottom ends and peel the thick lower portions of the spears with a vegetable peeler. Cook the spears in the salted water until very tender, 5 to 7 minutes. Remove from water and drain. Coarsely chop the spears, then puree in a blender or food processor until smooth. Set aside.
Step 3Heat the oven to 350 degrees. Melt 1 tablespoon of the butter and brush into 6 (one-half cup) ramekins, coating thickly. Arrange 3 tips in a fan shape in the bottom of each ramekin. Set aside.
Step 4Melt the remaining 2 tablespoons butter in a heavy saucepan over medium heat. Whisk in the flour and cook until smooth and bubbly. Gradually add the milk, whisking constantly. Bring to a boil and cook until thick. Season with one-half teaspoon salt and the nutmeg and cayenne. Remove from the heat and let cool slightly.
Step 5Mix the pureed asparagus into the bechamel, mixing very well. Add the eggs and mix well. Ladle into the ramekins.
Step 6Arrange the ramekins in a large baking dish. Place on the middle rack in the oven and pour hot water into the baking dish to come halfway up the sides of the ramekins. Bake 30 to 40 minutes, until a knife inserted into the center comes out clean. Set aside on a rack 15 minutes.
Step 7While the flans settle, heat the cream in a small saucepan. Add the Fontina and stir over medium-low heat until melted.
Step 8To serve, spoon 2 tablespoons of the Fontina cream on each of 6 small serving plates. Unmold the flans onto the plate and arrange the pea shoots on the side or in a wreath around each flan. Serve remaining sauce on the side.