I love the Outback Oven by Backpacker's Pantry. It was 1st made by Travelling Light and I've baked some very nice pastry with it. Other than a reflector oven (with which I've had 3 successful tries) the Outack Oven is the best way to bake when backpacking.
The oven is a fiberglass yurt-shaped pot cover W/ a hole in the center of the pleated top to release heat & view the aneroid thermometer/pot lid handle. Beneath the pot sits a corrugated stainless steel circular heat diffuser.
BUT you must have a very low simmering stove like the MSR Dragonfly or most remote burner canister stoves like the MSR Wind Pro. Despite their ad claims I found it impossible to get an Optimus Nova liquid fuel stove to simmer low enough to bake.
"There are no comfortable backpacks. Some are just less uncomfortable than others."