Heat the butter in a pan, add 1 cup of milk, sugar and bicarbonate of soda. Bring to the boil over medium heat and cook well stirring constantly with a wooden spoon until the mixture starts turning to a caramel color.  Then add another cup of milk and the brown sugar. Continue stirring and when the mixture starts thickened, add another cup of milk.

As it thickens again add another cup of milk and glucose, reduce the heat to low and continue stirring until the custard is thickened enough for you to see the bottom of the pan when you move the spoon through it or until a little custard put on a plate doesn't run.

You can use this as centre spread or filling with biscuits, pastries, cake or even bread pieces.