Cook the apples in a medium saucepan with the cinnamon for 5-10 minutes, stirring occasionally until they’re golden and soft.
Preheat your oven to 180Fan / 200C / 400F / Gas6 and line a 12 hole muffin tin with cases.
Make the streusel by rubbing the butter and flour together between your fingertips until there's no lumps of butter left. Then stir in the sugar and oats and set aside.
For the muffins put the milk and vinegar into a bowl, whisk, then set aside while you weigh out the dry ingredients. This curdles the milk slightly, giving a richer flavour.
In a large bowl put the flour, almonds, baking powder, bicarbonate of soda and sugar and mix together.
Whisk the oil and caramel flavour into the the milk and vinegar.
Pour the wet ingredients onto the dry ingredients and mix well, stirring up from the bottom of the bowl to make sure you don't leave any flour 'pockets'.
Divide the mixture evenly between your muffin cases.
Sprinkle over the streusel topping then, using your fingertips, lighly push it into the muffin batter - this helps prevent it falling off once the muffins are baked!
Bake for 25-30 minutes until risen and golden - test one of the muffins by inserting a cocktail stick into the centre of the muffin. It should come out clean, with no raw cake mix still clinging to it.
Leave to cool in the tin for 5 minutes before transferring to a wire rack to cool completely.
Store in and airtight container for up to 4-5 days or freeze.