Polenta without cornstarch

2 bunches swiss chard (about 3 1/2 pounds) or 2 bunches bok choy 1 tablespoon olive oil 3 garlic cloves , thinly sliced 1/4 teaspoon crushed red pepper flakes[...]

1 (10 ounce) package frozen chopped spinach , thawed 1 (10 ounce) package frozen chopped kale, thawed 2 tablespoons olive oil 1 small onion , finely chopped 2[...]