Put the chiles in a small saucepan. Cover with water, bring to a boil, reduce the heat, and simmer, uncovered, for 15 minutes. Remove the pot from the heat, cover it, and let the chiles soak for 10 to 15 minutes; drain. Put the chiles in a blender, add the garlic and 1/3 cup water, and blend for at least 1 min., starting at low speed and gradually turning to high speed, to make a purée; set aside.
Melt 1-1/2 tsp. of the butter in a small skillet over medium to medium-low heat, add the almonds and cook, stirring often, until they are golden brown but not burned. Pour onto a plate and set aside.
Heat the olive oil and the remaining butter in a large pot or Dutch oven (with a good lid) over medium heat, add the rice and onions, and sauté, stirring frequently, for 5 to 6 minutes. The rice and onions should be starting to turn golden. Turn the heat to between medium and medium high, stir in the chile purée, and continue cooking, stirring every 30 seconds, until almost all the moisture has evaporated and the rice no longer sticks together, 7 to 10 minutes. Add the broth, milk, salt, oregano, and thyme, stirring to mix well. Bring the liquid to a boil, cover the pot, turn the heat to very low, and simmer for 20 minutes. Turn off the heat, stir in the toasted almonds, cover the pot, and let the rice steam, off the heat, for about 15 minutes. Serve with a dollop of the sour cream and the avocado.