Heat the oil in a large wide saucepan over medium heat. Add the minced garlic and chopped shallots, and cook for about 30 seconds.
Add the curry paste and curry powder, and cook for another 30 seconds, stirring constantly.
Add the coconut milk, broth, thinly-sliced chicken (thighs or breast), fish sauce, and sugar.
Stir everything together, scraping up any curry paste that has stuck to the bottom of the pan. Taste and adjust seasoning, including adding more red curry paste if needed to bring the right amount of heat.
Bring to a gentle boil, then lower heat and simmer uncovered for about 30 minutes. Taste and adjust seasoning.
Meanwhile, bring a large pot of water to a boil. Add a lot of salt and the noodles, and cook the noodles according to package directions (you want al dente), timing it so that the noodles will be cooked when the curry is done simmering.
Drain the pasta and divide between two bowls. Pour your curry and chicken mixture over the top, and add garnishes of your choice. Serve immediately.