1. In a medium saucepan, melt the butter over medium-high heat.
2. Add leeks and shallots, cook until leeks are tender. Do not brown.
3. Add champagne and reduce until about 2-3 tablespoons.
4. Add lemon juice and cook until liquid evaporates.
5. Add cream and simmer until slightly reduced. Season with salt and pepper. Keep warm.
6. Mix together the almonds, parsley and lemon zest in a small bowl, set aside.
7. Season the halibut with salt and pepper with the flour in a bowl; dredge the halibut in flour, shaking off flour.
8. Lightly brush one side of the halibut with the beaten egg. Press egg side of halibut into almond mixture.
9. Working in two batches. Heat half of the olive oil in a large sauté pan over medium-high heat. Add half of the halibut to the sauté pan, almond side down, and cook until crust is nicely browned.
10. Turn the halibut over, reduce heat to medium and continue to cook until opaque in the center, about 7-8 minutes.
11. Place the warm sauce on a plate and place halibut on top of sauce.