Lower the flame. Melt 2 Tbl of butter with the bay leaves in the pressure cooker. Throw in the onions. Saute until they are clear. Add the rice and saute until the grains becomes slightly aromatic. Pour in the chicken stock. Return the thighs to the pan. Add salt, black pepper and cayenne pepper to taste. Lock the lid on the pressure cooker. Raise the heat to medium-high until the pressure cooker begins to hiss and spit. Adjust the heat (to medium or medium-low) so that a constant, slow stream of vapor shoots out. Pressure cook for 20 minutes at 15 psi. Shut off the heat. Allow the cooker to de-pressurize naturally. Remove the lid and turn the rice. Replace the lid. Allow the rice to rest for another 10 minutes.
Pick out the bay leaves. Turn the chicken and rice out onto a large platter. A knob or two of butter melting overtop of the rice enhances the dish radically.