With a whisk mix the butter, lime zest and sugar until you have a creamy texture.
Add the eggs and oil and mix again.
Add the honey, lime juice, milk, chia seeds and mix.
Add the flour, baking powder, salt and mix with a spatula until you have a homogeneous mix.
Put mix inside each muffin case in the mould.
Put all the ingredients in a bowl and pinch the butter with your hands along with the other ingredients so the butter cubes become smaller and smaller. Stop when you can't feel any lumps of butter and it looks like wet sand.
Put the cumble on the muffins.
Take to a preheated oven at 180C for 20-25min or until the dough is completely cooked. You know this has happened when you insert a knife or skewer down the center and it comes out without any uncooked dough.
Decorate with a mini slice of lime cut in 4.