Make Cauliflower Mash according to recipe, adding in your 2 tablespoons of sour cream. Heat olive oil in a large pot. Add beef, season with salt and pepper and seal. Remove and set aside.
Heat butter and add mushrooms and onions. Cook, stirring frequently until onions start to soften. Add back beef, add coconut flour and cook for a few minutes, stirring.
Add tomato paste and bay leaves and stir to combine. Add stock one cup at a time, stirring well after each addition.
Bring to the boil, reduce to a simmer and cover. Simmer for 1 ½ - 2 hours until sauce has reduced and thickened. Pour into a deep pie dish.
Cover with your Cauliflower Mash, spreading it out over the pie filling. Bake in the oven at 180C for 20-25 minutes or until Cauliflower Mash is golden. Make sure to place a foil lined tray on the shelf under your pie dish to catch any liquid that boils over the sides.
Remove from the oven, allow to cool off a little and serve.