Make the caramel
Caramel seems to be unbuyable at present, but the method of boiling for 3 1/2 hours was a little too much effort. So we tries using the oven instead, which worked very well.
Preheat the oven to 220C.
Pour the condensed milk into a glass pie plate or shallow baking dish (I used a tall souffle one).
Set the dish in a roasting pan and add hot water until it comes halfway up the side of the dish.
Cover the dish tightly with foil and bake for 1 to 1 1/4 hours. Check during baking and add more water if needed.
Remove and leave to cool.
Whisk until smooth.

Make the biscuit base
1 packet hobnobs (350g)
150g butter

Melt the butter and add the crushed biscuits.
Press into a flan dish and refrigerate.

Spread caramel over the biscuit base.
Slice the bananas and spread over the caramel.
Whip the cream, adding 1 tsp crushed instant coffee. Spread over the bananas.
Sprinkled with a little more powdered coffee.

Make the mini-pies in the same way in silicone muffin cases or ramekins.

Addendum
Variations from 2 years ago, to avoid their being lost.
Banoffee Cake
I made 2 sandwich sponge cakes and sliced each in half horizontally. I then prepared some whipped cream with coffee and layered toffee, bananas, and cream on each slice. Mmm.

Banoffee-fudge cupcakes
I also made sponge cupcakes, with the addition of small chopped up chunks of fudge. I think another time I’ll try flouring them before mixing them into the batter, or use a butter-based cake recipe, as they sank to the bottom of my cupcake liners (and melted and tasted delicious). I then topped each cupcake with toffee, a slice of banana and piped on a swirl of coffee-whipped cream.
Decadence in a bite!

And my comment from back then bears repeating:
Of course the nicest part is that you can just put your spoon into the tin of toffee and eat up a spoonful – all by itself!

This is the birthday cake I made for the Penguin 2 years ago, which he specially requested a repeat of. I changed it up with coffee-caramel instead of coffee glace icing. I didn’t have a Penguin Taste Tester at my side for the various stages this time, but the end result was pronounced perfection.

Coffee cake
200g / 4oz butter (Cunningly softened by sitting it on top of the boiled kettle)
200g / 4oz sugar
4 eggs
200g / 4oz self raising flour
3 tbsp coffee dissolved in 3 tbsp hot water (this is an increase on the first time I made it – my recipe note states “not enough”)

Heat oven to 180C.
Grease 3 tins and line bases with greaseproof paper (this is important – the tops of my cakes stuck this time, because I left out the paper).
Cream the butter and sugar until light and fluffy.
Beat in the eggs, one by one, adding some flour with each. Fold in any remaining flour.
Bake for 20-25 minutes (15 in a fan oven).
Prick the hot cakes and pour Coffee Syrup* over them. Leave to cool in tins until completely cool.

*Coffee Syrup (for 3 cakes)
3 tbsp coffee
6oz / 50g demerara sugar
165ml / 6 l oz boiling water
Pour the water over the sugar and coffee and stir until dissolved.
The syrup makes the cake really lovely and moist. You can see the dark areas where the syrup has soaked in below.

Coffee buttercream
100g / 4 oz butter
200g / 8 oz icing sugar
4 tsp coffee (Or 5/6?)

Cream the fat, gradually adding the icing sugar.
Add the coffee.
Spread onto cake between layers. Reserve a small amount.

Coffee caramel
Half a can of caramel (condensed milk tin size)

Place the caramel in the buttercream bowl, mixing with the remaining buttercream for the coffee-y flavour. Spread over the top of the cake after crumb-coating.
Top with mini-smarties and chocolate penguins (made with the chocolate left over from 2 lava puddings… there was just enough for 3 penguins).

The original glace icing, for reference
100g / 4oz icing sugar (or maybe double)
1 tbsp warm water (half and half water and coffee to taste)
Spread onto cake and leave to set.

Another alternative, not yet tested
500g mascarpone
85g muscavado sugar
4tbsp tia maria
Beat until smooth.