Preheat the oven to 275 degrees F. Mix 2 tablespoons butter, the garlic, lime zest, 1/2 teaspoon salt and a few grinds of pepper in a small bowl. Coat a rimmed baking sheet with cooking spray. Place the salmon skin-side down on the prepared baking sheet and spread the lime butter evenly over the top. Bake until the salmon is just cooked through, 20 to 25 minutes.
Meanwhile, melt the remaining 1 tablespoon butter in a large skillet over medium-high heat. Add the shallots and cook, stirring, until soft and translucent, 3 minutes. Add the tomatillos and cook until slightly soft, about 4 minutes. Add the corn and chile pepper. Cook, stirring often, until warmed through, about 6 minutes.
Remove the skillet from the heat and stir in the crema, cilantro and half of the lime juice; season with salt, pepper and more lime juice. Cut the salmon into 4 pieces and serve with the creamed corn.