Huge rice cake fan. I make them in 6-bar portions, which last about a week. Notes and general recipe:
-First off, soak your rice for 5 minutes in enough water to cover it plus 1 tablespoon hydrogen peroxide, then rinse rice well. This makes the bars last way longer and prevents possible digestive distress due to bacterial spores that commonly live on rice. Info here: Rice Science +How to Help your Rice Cakes Last Longer - Skratch Labs
6-bar recipe:
1 cup short grain rice, 1.5 cup water, 1/2 teaspoon salt. Cook rice for 15 min., kill heat and let stand for 10 min.
Add to cooked rice and mix well:
1/4 C sugar
1/4 C coconut milk
1 T lemon juice
Add half your rice to a ~6"x8" container (I use a large Tupperware), mash down to make a single flat layer. To the top of this add topping of your choice. I have enjoyed:
-100g Nutella
or
-50g nut butter + 80g jam of your choice
Then add the rest of the rice and mash it flat on top.
FULLY CHILL (overnight ideally) then cut into 6 bars and wrap in Skratch Paper. These will keep in the fridge for at least a week. Downing one of these with coffee ~30min before a trainer session is a great way to get some carbs to the muscles.
I also really enjoy an umami version, similar to above with some more salty/tart ingredients. If you really need electrolytes, do as above but add a THIN layer of Vegemite, remarkably excellent hours into a sweaty ride!