To a medium-sized bowl, add the shrimp, beer, and cilantro, turning the shrimp in the beer to coat. Then let it stand at room temperature while you proceed with the recipe.
In a large skillet, heat the olive oil over moderately high heat until ripples appear in the bottom of the skillet, 1½ to 2 minutes. Add the onion and garlic and sauté, stirring now and then until wilted, about 3 minutes.
Set the skillet off the heat and drain the beer from the shrimp directly into the skillet. Add the tomatoes and chipotle pepper, return to moderately high heat, and bring to a quick boil. Adjust the heat so the mixture bubbles gently, and simmer uncovered until it's the consistency of pasta sauce, about 15 minutes.
Add the shrimp and cilantro, cover, and cook over low heat just until the shrimp turn pink and are cooked through, about 5 minutes (don't overcook).
Place the hot pasta into a large bowl, add the shrimp mixture, and toss well.
To serve, divide the pasta among four heated dinner plates and top each portion, if desired, with sprinklings of grated cheese and chopped cilantro.
Notes
You'll probably want to pass additional grated Parmesan for those who like more.
Feel free to use your favorite pasta in place of the spaghettini, if desired.