Place the boneless skinless chicken thighs, finely diced yellow onion, chopped cremini mushrooms, and frozen assorted vegetables into the slow cooker. Add in the homemade Italian dressing blend, salt, black pepper, and chicken broth. Stir gently to combine. Set the lid on the slow cooker.

Cook on high for 2-3 hours or on low for 4-6 hours, until the chicken is fully cooked and tender. If you're busy, the low setting is a safe go-to; high heat works great if you're short on time.

Once the chicken is cooked through, carefully remove it from the slow cooker. Use two forks to shred the chicken into bite-sized pieces. Set aside the shredded chicken for now.

Stir in the heavy cream to the vegetable and broth mixture in the slow cooker. If you'd like the soup to be thicker, stir together the cornstarch with an equal amount of water to create a slurry and add it as well. Return the shredded chicken (from Step 3) to the slow cooker and stir everything together. Set the slow cooker to high heat so the mixture simmers gently.

In a small bowl, whisk together the all-purpose flour, baking powder, salt, egg, and milk until just combined into a smooth batter. Be careful not to overmix—it's fine if there are a few lumps. I find that letting the batter rest for a few minutes results in fluffier dumplings.

Drop large spoonfuls of the dumpling batter (from Step 5) over the simmering soup and chicken mixture. Cover the slow cooker and cook on high for 30-60 minutes, until the dumplings are cooked through and set in the center. The timing will depend on the size of your dumplings and the heat of your slow cooker. For extra flavor, I sometimes sprinkle a little black pepper on top before serving.