Boil the beets in water, covered, for approx. 40 minutes (depending on their size) until tender but still quite firm. Strain and leave the beets to cool. Peel and puree.
Preheat the oven to 400 F/ 200 C/ gas mark 6. Lightly grease or line with paper cases a 12-hole muffin pan and set aside.
In a bowl combine the flour, ground almonds, baking powder, pinch of salt and chocolate chips and stir with a whisk. Set aside.
In another large bowl (briefly) whisk together the eggs with oil and sugar until smooth. Pour in the beet puree and milk and stir thoroughly. Add in the flour mixture all at once and stir just to combine.
Spoon equal amounts of the muffin batter into your muffin pan and bake in the centre of the oven for 23 minutes. Remove from the oven and place on top of a cooling rack for 10-15 minutes.
To save time you can boil the beetroot ahead. See the post for details.