Pre-heat oven to 350°F. Lightly greasy or spray bottom and sides of a metal 9x13 cake pan.
In your stand mixer with wire whips, or a large bowl with a hand mixer, mix peanut butter and sugar until fluffy (1-2 minutes). (For fastest, easiest mixing, use a stand mixer like my Bosch Universal Mixer)
Pour in maple syrup, egg, and coconut oil and mix until well incorporated (2 minutes).
Mix in vanilla and salt.
If using a stand mixer, add the chocolate chips, then the oatmeal, and let run until well combined. If using a hand mixer, put it aside and add the chocolate chips and oatmeal by hand.
Press mixture into greased pan and push down hard until flat and smooth; using the bottom of a measure cup works great.
Bake at 350°F for about 15 minutes, depending on your oven. Watch the top and sides every minute starting at 15 minutes, when both the sides are brown, and the top is set (not shiny) and doesn't smoosh down when lightly poked, remove from oven. That comes at 15 minutes in our oven.
Set pan on wire rack. Let cool in pan for 15 minutes to allow a firm set. Flip onto cutting surface and let fully cool.
Cut horizontally into 9 long bars, then one long cut down the middle. Or however you prefer. Wrap completely in plastic wrap and store at room temperature up to 1 week. May be refrigerated up to 2 weeks and frozen up to 6 months (if freezing, wrap an extra layer over them to protect from freezer burn).