The easiest way to start this recipe is get everything prepped; Cut the chicken into cubes, put milk and chicken stock in a 2 cup measuring cup, cut 2 tbs of butter and set aside, get 2 tbsp of flour and set aside.
Add olive oil to pan, once hot add chicken in and season with season salt (add more of less depending on your preference).
Cook chicken until browned, remove from pan and set aside (a bowl works best- it holds all those great juices in)
Add your prepped 2 tbsp of butter and flour to the same pan as chicken and stir together until it makes a paste, this is called a roux.
Once the roux is mixed well and starts bubbling, add in your milk/chicken stock mixture. Bring your heat up to medium and stir together with the roux. Stir together until sauce gets nice and thick and starts boiling.
Reduce heat to low and add in your mustard (start with a cup), stir into sauce until well blended. Taste- add mustard if needed.
Stir chicken back into the sauce, make sure you add all the juices as well.
Serve over your choice of pasta! Bon Appetit Optional- Sprinkle with parsley and paprika