Slice bananas into 1⁄4”-thick rounds and put in a ziplock plastic bag. Lay the slices flat in a single layer in the freezer so the rounds freeze individually and not in a big clump. Freeze the bananas for at least 2 hours and up to overnight.
Place the frozen bananas, peanut butter, coconut oil, cinnamon, nutmeg, and salt in a food processor or blender and let sit for 2 or 3 minutes. Then puree until creamy and smooth.
If you like a frozen yogurt consistency, then serve it up. If you like a firmer ice cream experience, spoon it into a container and freeze for about an hour.