Preheat the oven to 150°C.
Heat the olive oil and butter in a large lidded casserole dish on the hob.
Cook the diced onions until softened but not browned.
Add the garlic, bacon, and mushrooms and cook for one minute.
Brown the venison in a frying pan in small batches and add it to the casserole dish.
Add the wine, water, stock cubes, redcurrant jelly, salt, and pepper.
Bring the mixture to a boil and stir well.
Cover the dish and cook in the middle of the oven for 90 minutes.
Mix the cornflour with 30ml of water to create a paste.
Stir the paste into the casserole gradually until the desired thickness is reached.
Cook on the hob over low heat for 5 minutes until the gravy thickens.
Serve with potatoes and spinach, garnished with herbs and redcurrants.