In a pan saut the mushrooms in butter till brown and soft. Keep aside.
In a deep-bottomed pot/cesserole, saut the bacon in 1 tbsp oil over moderate heat for 2 to 3 minutes to brown lightly.
Remove to a side dish with a slotted spoon. Reheat the pan until fat is almost smoking before you saut the beef. Saut the beef in the bacon fat in batches making sure not to crowd the pieces (the pieces need to brown on all sides, not sweat).
Add the browned pieces of beef to the bacon. Lower the heat to medium. In the same fat, add the onions, shallots and carrots. Cook till the carrots soften.
Add the cooked veggies to the beef and bacon.
Pour out the sauting fat.
Return beef to the casserole. Then sprinkle on the flour and toss to coat the beef lightly with the flour. Stir everything around till the flour is cooked and no white traces of it remain.
Add the bacon and veggies and season with salt and pepper. Stir in the cognac and enough stock so that the meat is barely covered.
Add the garlic, thyme, parsley, tomato paste and bay leaf. Bring to simmer on top of the stove. Cover the casserole and set it in the oven. Cook for 2 1/2 to 3 hours. About 1 hour into the cooking add the mushrooms and stir in the cocoa powder. Return to the oven. The stew is done when the meat is fork-soft.
