Grease and line a 20cm (8") square baking tin and set aside (see my notes for alternatives).
Place sweetened condensed milk and milk chocolate in a large bowl.
395 g sweetened condensed milk, 180 g milk chocolate
Heat in the microwave in 30 second bursts (mixing between each burst) until melted.
Add biscuits crumbs and golden syrup (if using) and mix to combine. Allow mixture to cool slightly.
250 g Malt-O-Milk biscuits, 2 tablespoon golden syrup
Mix in chopped Maltesers.
280 g Maltesers
Press mixture into tin and smooth the top.
Chocolate Topping
Place milk chocolate and vegetable oil (if using) in a small bowl and heat in the microwave in 30 second bursts (stirring between each burst) until melted and smooth.
180 g milk chocolate, 1 tablespoon vegetable oil
Pour melted chocolate over the base then scatter over remaining chopped Maltesers. Place in the fridge to set.
Notes
Because we aren't baking this slice, there is no need to find a baking "tin" of a suitable size - you could use a plastic container instead if you like.
You could also use a bigger tin, your slice will just be a bit thinner.
It's still necessary to grease and line whatever tin you put this slice in to set. This will help you get it out of the tin later.
I use a food processor to crush the biscuits, but if you don't have one just put them in a sturdy plastic bag and give them a bash with something solid like a rolling pin.
Allowing the mixture to cool slightly after the biscuit crumbs are mixed in just ensures that all of the chocolate outer shell doesn't melt off the Maltesers.
Time to slice but it won't come out of the tin? Just sit the base of your tin in hot water for a couple of seconds then it will come out freely..
*Please note that the amount of calories per serve is provided as a guide only, as ingredients and cooking methods can vary greatly*