Juice the apple and carrot and add in lemon juice to yield about 500ml juice.
Put juice, butter and sugar into a pot and bring to the boil. Boil for 8 minutes.
Add pectin and minced habaneros to pot and cook a further minute, or until the gel sets on the back of a cold metal spoon.
Place clean jars in boiling water and when warmed through place on a wooden board or a cloth. This prevents thermal shock and the glass breaking.
Using a funnel, pour the hot jelly into the jars and seal tightly with sterilised lids. Leave on the board until cooled.
If you do not wish all the minced chillies to sit on the top of the jelly you can either remove them before pouring into the jars or swirl the jars as they near cooled state.
For less heat do not add the seeds. If habanero chillies are unavailable, you could use Scotch bonnets, which are similar in heat and flavour.
Habaneros are caustically spicy. Use rubber gloves when handling and seriously consider using eye protection. You will not be harmed if it touches your skin but it will hurt with a pain you will remember to your dying day.
Instead of juicing the carrot and apple, you can speed things up and buy apple and carrot juice from the store and use around 200ml carrot juice and 300ml apple juice.