Grab a large bowl and add 2 tablespoons of olive oil, dijon mustard, garlic cloves, 1 shallot, paprika, and salt & pepper to taste. Add the chicken to the bowl and mix until the chicken is coated.
Grab your instant pot and push the [saute] button. Choose the [high] or [more] setting. Add the remaining 1 tablespoon of olive oil and heat it for about 30 seconds - 1 minute. Add the chicken breasts and sear on both sides (about 2 minutes per side) until golden. Add the butter, lemon slices, and the other shallot and saute with the chicken for 2 - 3 minutes. Add the chicken broth to the instant pot and deglaze (scrape) the bottom of the pan to get all those flavors mixed into the broth. Add the orzo and smooth it until it is completely submerged in the broth and surrounding the chicken. Top with the spinach BUT (!!) do not stir it in. Simply allow it to rest on top of everything.
Secure the instant pot lid and hit cancel (to turn off the saute function). Hit [Manual] or [pressure cook] at high pressure for 6 minutes. Do a quick release when the food is finished cooking.
When the pressure is released, remove the lid and stir the spinach into the food so everything is evenly distributed.
Serve the chicken and orzo warm. Optional: top it with feta cheese crumbles for a pop of flavor.