Preheat oven to 350 degrees F. Thinly slice half of the jalapeño and set aside. Remove seeds if desired, and finely chop remaining half of the jalapeño to equal about 1 1/2 Tbs.
Heat a large nonstick skillet over medium-high heat. Add chorizo, and cook, stirring occasionally to crumble, until just starting to brown, about 2 minutes. Add onion and chopped jalapeno, and cook, stirring occasionally, until onion is softened, 6 to 8 minutes.
Arrange tots in an even layer in a lightly greased 1 1/2-qt. baking dish. Top with chorizo mixture and cheese. Whisk together eggs, milk, and salt. Pour egg mixture over tots.
Bake casserole until golden brown and set in the middle, about 45 minutes. Drizzle with Mexican crema and top with sliced jalapeno.