Heat a gas grill to medium-high or start a charcoal fire and let it burn until the coals are covered with gray ash, but the fire is still quite hot; for the smokiest flavor, throw on a few soaked wood chips just before beginning to grill. Lay the tomatoes, habanero chiles and 1 head of unpeeled garlic on the grill (it's easiest to use a perforated grilling pan, so nothing sticks or falls through the grates) and cook, turning regularly, until everything is soft, blackened and blistered, 8 to 10 minutes.
In a blender or food processor, blend the olive oil with 2 cloves of peeled garlic, 2/3 cup of the chopped cilantro and 1 teaspoon salt. Smear it over both sides of the salmon. Lay the salmon on the hottest part of the grill. When it is marked underneath, flip the pieces and mark them on the other side - the salmon should still be rare. Remove to a cooling rack set over a plate.
Turn the oven on to 375 degrees. When handleable, peel the grilled tomatoes and garlic; discard the peels. In a blender or food processor (in batches if necessary), blend the tomatoes, garlic and habaneros to a coarse puree. You should have a little over 4 cups of puree. Stir in enough water to bring the quantity to 6 cups. Taste and season with salt, usually about a scant 2 teaspoons. Remove 1 cup of the salsa and set aside.
Mix the ricotta, half of the crema, eggs and remaining cilantro. Spoon 1/4 of the sauce over the bottom of a 9 x 13-inch baking pan. Arrange 4 of the pasta sheets over the sauce (it's okay if they slightly overlap; because they expand, they won't completely cover the sauce). Next, spoon on another 1/4 of the sauce, then 1/2 of the ricotta. Make another layer using 4 pasta sheets, another 1/4 of the sauce and the remaining ricotta. Make a final layer of 4 pasta sheets (there will be 4 sheets from the box left over), the remaining sauce and all the shredded cheese.
Cover with foil and bake for 45 minutes. Uncover and continue baking until the cheese is browned, about another 10 minutes. Let stand about 15 minutes, lightly covered with foil, before cutting and serving. (For the most attractive presentation of the lasagna, let the lasagna cool completely - you may refrigerate it, if working ahead - then cut it into neat serving pieces, lay on a parchment-lined baking sheet and reheat for about 15 minutes at 350 degrees.)
While the lasagna is resting, briskly simmer the reserved 1 cup of sauce until quite thick (it will have reduced to half the original volume), then stir in enough chicken broth or water to give the mixture a saucy consistency. Reheat the salmon in the oven - it should take about 5 minutes to warm through to about medium-rare.
Cut squares of the lasagna and serve each piece with a drizzle of the warm sauce all around, topped with a piece of salmon, a spoonful of the remaining crema, and shower of remaining cilantro.