Place the bacon in the Instant Pot and set it to ‘sauté’ mode. Cook the bacon until soft but not yet crispy.
Stir in the onions, carrots, and celery and cook until the onions are translucent.
Add the garlic, salt, and pepper, stirring until fragrant.
The bottom of the pot should still have quite a bit of leftover fat from the bacon. If not, add 1 tablespoon of olive oil before adding the split peas.
Stir in the split peas, then pour in 6 cups of the chicken stock, reserving the remainder for later use.
Add the ham and thyme sprigs and seal the lid.
Select the ‘soup/broth’ mode on the Instant Pot set to ‘normal’ high pressure. Cook for 20 minutes.
While the soup is cooking, pour the remaining 2 cups of chicken stock into a medium bowl. Add the frozen peas and blend with an immersion (or stick) blender until smooth.
Open the lid, discard the sprigs of thyme, and pour the blended peas (1 cup at a time) into the Instant Pot until you have reached the desired color and consistency.
Season the soup with salt and pepper to taste, and let it sit for 5 minutes to thicken before serving.
Serve with optional baguette slices, cubed bread, or parsley.