Your stove should be on a 40 amp circuit, which requires 8/3 Romex cable. Change the breaker from the 40 amp twin breaker to a 20 amp twin breaker then make the stove receptacle box a junction box where you splice some 12/3 Romex to the 8/3 Romex and then run the 12/3 to a duplex 20 amp receptacle with the tie on the hot side removed. This will give you two 20 amp receptacles.
Help with DIY dedicated circuit
I am wanting to install a dedicated circuit for my amp, but getting from my panel to the wall behind my amp is going to be difficult. As I was investigating in my attic, I realized that when I changed my stove from electric to gas, the unused 30 amp Romex 10/3 wire will reach within 15 feet of where I want the wall outlet. Do I install a junction box and run Romex 10/2 to the new wall outlet and use the 30 amp breaker? What is the best way to connect the wires in the junction box?