Bring a large saucepan of water to a boil. Slice the poblanos in half lengthwise and remove the seeds and stems. Place cleaned peppers in boiling water; cook until soft, about 4 minutes. Drain.
Heat olive oil in a large skillet. Stir in vegetarian crumbles and chili seasoning mix. Cook, stirring, until crumbles are hot, about 5 minutes. Fill the cooked peppers with the seasoned crumbles; top with pepperjack cheese. Arrange stuffed peppers on a baking sheet.
Place peppers in preheated oven until cheese is melted, about 10 minutes.