Slice mushrooms. Finely chop onion. Crush garlic. (If using optional but awesome bunch sausages, cut them into 1cm pieces) Melt butter in a large frying pan, then add onions, garlic, and mushrooms (and brunch sausages if using) until the onions are softened. (Probably like a medium-high heat) Mix in 2 tablespoons of plain flour into the pan until everything is covered. Looks weird and chunky, but trust me - it’s gonna be ok. Pour in chicken stock. Heat and stir continuously until thickened slightly. Separately mix the cream in with the final 1 tablespoon of plain flour and all seasonings. Try to get rid of as many lumps as possible before adding the mixture to the pan. Keep stirring until thickened and any remaining lumps are worked out. Serve and nom :-)