Butternut Squash Black Bean Tostadas

For the Tostada Shells:

• 6 blue corn tortillas
• cooking spray
• salt

For the Butternut Squash:

• 1 medium butternut squash peeled, seeded and cut into 1/2-inch cubes
• 1 tablespoon olive oil
• 1/2 teaspoon ground cumin
• 1 tablespoon lime juice
• salt and black pepper to taste

For the Creamy Avocado Dressing:

• 2 ripe avocados peeled and seeded
• 1/2 cup low-fat buttermilk
• 2 cloves garlic minced
• 1/4 cup chopped fresh cilantro
• 2 tablespoons chopped green onion
• 1 small jalapeño pepper chopped and seeds removed
• 2-3 tablespoons fresh lime juice
• 1/4 teaspoon ground cumin
• salt and ground black pepper to taste

Tostada Toppings:

• 2 15 ounce cans black beans, rinsed, drained, and heated
• 1 small red onion diced
• 1/2 cup Pepitas
• chopped lettuce