Heat olive oil in a pressure cooker over medium-high heat. Saute onion until translucent but not browned, about 5 minutes. Add squash, broth, sweet potatoes, apples, garlic, cinnamon, nutmeg, black pepper, cumin, ginger, and salt.
Close and lock the lid. Bring to high pressure according to manufacturer's instructions, 10 to 15 minutes. Reduce heat to medium-low; cook until squash and sweet potatoes are fork-tender, about 15 minutes.
Release pressure carefully using the quick-release method according to manufacturer's instructions. Unlock and remove lid. Liquefy soup using an immersion blender. Stir in half-and-half. Serve with a dollop of yogurt on top.
Use homemade vegetable stock and/or yogurt if possible.
If you don't have a high quality vegetable peeler, it may be difficult to peel the squash. You can either put the squash and 2 tablespoons water in a slow cooker on High for the day, or quarter squash, place on a trivet in pressure cooker with 1 cup water, and cook at least 10 minutes.
Add carrots if desired.
You can also transfer in batches to a food processor or blender in step 3, but make sure that there is enough liquid in each batch.
Per Serving: 313 calories;12.1 g fat;
49.6 g carbohydrates;
6 g protein;
26 mg cholesterol;
598 mg sodium.