On a cutting board, smash the garlic cloves, sprinkle with 1 teaspoon of the salt, and, with the flat side of a large knife, mash and smear the mixture to a coarse paste. Put the garlic, beans, chili powder, water, and olive oil in the bowl of a food processor and blend until smooth. Spread in the bottom of a 2-quart casserole or gratin dish, or in individual sized dishes, as desired.
Scatter the cheese over the beans. Halve and seed the avocados, then mash with the jalapeno and another teaspoon of salt in a small bowl. Spread a layer of the avocado over the cheese, and then scatter the lettuce on top.
Mix the yogurt with the cilantro and then spread over the lettuce. Add a layer of tomatoes and, finally, scatter the scallions on top. Chill until ready to serve. Garnish with a few cilantro sprigs and serve with baked chips.