In a small microwaveable bowl, add the chopped sweet potato and a small amount of water. Cook 7-8 minutes on high, until soft. (some microwaves will only require 5 minutes--check at 5 minutes)
In the bottom of a large pot or sauce pan (I use the same pot the orzo cooked in), add the olive oil and heat until shimmering.
Add the sage, pancetta and onion. Saute for 3 minutes or until the onion is translucent.
Add the garlic and peas and saute just until the garlic is fragrant, about 1 minute.
Remove the pea and pancetta mixture from the pan and set it aside, add 1 tablespoon more of olive oil.
Add the sweet potatoes and saute just to remove the pan drippings.
Add the pasta water, milk, salt & pepper.. Bring just until boil and remove from heat.
Use an immersion blender, blender, or food processor to puree the potatoes with the pasta water and milk.
Add the pasta back into the sauce (NOTE! Add only half of the pasta, to start. Determine how saucy you like your pasta before adding additional in. Sometimes we only use about 3/4 of the pasta)
Stir in the pea and pancetta mixture.
Add salt, pepper, and milk as desired.
Serve immediately with shaved Parmesan Cheese.