Slow Cooker Vegetarian Chili

Ingredients

• 2 teaspoons canola oil
• 1 large onion, diced
• 2 stalks celery, diced
• 2 carrots, diced
• 2 cloves garlic, chopped
• 1 bell pepper, diced
• 2 tablespoons dark chili powder
• 2 teaspoons ground cumin
• 1/4 teaspoon red pepper flakes
• 1 (29-ounce) can crushed tomatoes
• 3 (15.5 oz) cans red kidney or black beans, rinsed and drained
• 12 ounces butternut squash, peeled and diced (about 3 cups)
• 1 cup vegetable stock