This is to be made before camping / hiking, not during, but:

Calorie Dense Flapjacks

Ingredients

180g butter
60g brown sugar
4 tablespoons maple syrup

250g porridge oats
50g mixed nuts
150g dried cranberries (or raisins)
1/2 teaspoon cinnamon

200g dark cooking chocolate

Steps

1. Pre-heat the oven to 180°C

2. Melt the butter in a saucepan with the sugar and maple syrup.

3. Once melted into an homogenous liquid, add the oats, nuts, cranberries, and cinnamon. Mix well until everything has an even coating.

4. Spread onto a baking tray and bake in the oven for 15m.

5. Remove from the oven to cool.

6. Once cooled, melt the chocolate and spread on top.

7. Allow to cool and restrain yourself from consuming until out in the hills.

For the sake of simplicity I often don't bother melting the chocolate on top, and just take it separately.