B737 Captain reported encountering wake turbulence that resulted in an aircraft upset at FL340 in trail of an Airbus.

Narrative

At about 20 to 25 minutes into the flight; the aircraft was in the process of leveling off at flight level 340 with the autopilot engaged. There was just a little bit of light chop; seat belt sign was on; the flight attendants were up. As the aircraft started the level-off it rolled aggressively about 30 to 35° to the right and pitched up what I believe was around 5 to 7°. I immediately grabbed the controls and started the recovery maneuver; push roll thrust stabilize. The aircraft rolled several times; each time I had to do the recovery maneuver. For a second I thought that I had a flight control problem because the flight controls weren't responding the way I was expecting due to the rolling action of the wake. Once stabilized at FL340 we advised ATC that we think we encountered wake turbulence. The controller's response was; 'Yeah there was a heavy Airbus up there. Contact Washington Center.' I called the flight attendants and asked how they were and if there was any damage or injury. They said they were OK and just some spilled drinks in the galley.