Preheat the oven to 350°F or about 170°C (160°C for fan ovens).

Grease a 7-inch square pan and line the bottom with baking parchment.

Put the mincemeat in a small bowl and stir in the rum, brandy, Cointreau or Grand Mariner. Set aside.

Combine the flour with the butter in a medium bowl and cut the butter into the flour until mixture resembles fine crumbs. You can use a food processor for this or do it by hand with an old-fashioned pastry blender.

Add the oats, baking soda, salt and sugar to the butter and flour mixture and mix thoroughly.

Press half of this mixture into the prepared pan.

Put the pan in the freezer and the remaining oat mixture in the fridge.

After 15 minutes, remove the square pan from the freezer and the remaining oat mixture from the fridge.

Carefully spread the boozy mincemeat over the top of the oat mixture in the square pan.

Gently sprinkle the remaining oat mixture evenly over top of the mincemeat.

Bake in the oven for about 25 to 30 minutes or until the squares are lightly golden brown.

Remove from the oven and allow to cool, then place the squares in the pan in the fridge for about half an hour or so before cutting.

Once the squares are cut, it's best to allow them to come to room temperature before serving.

Leftovers will keep in a sealed container in the fridge for several days.