In a small bowl, beat cheeses, garlic, lime zest, oil, chili powder and pepper flakes until blended. Stir in onion and cilantro. Refrigerate 1 hour or until firm.
With a small melon baller, scoop out avocado balls onto a baking sheet; sprinkle with lime juice. Shape 1-½ teaspoons cheese mixture around each ball, then roll in pumpkin seeds. Place on a waxed paper-lined baking sheet. Refrigerate until serving. If desired, serve with pretzel sticks.
