Preheat the oven to 200°C. Line a 12-hole muffin tin with muffin cases.
In a large mixing bowl, cream together butter and sugar until light and fluffy. Beat in eggs one at a time, mixing well in between each one.
Then sift in both flour and baking powder and fold through the mix with a spoon. Add lemon zest and fold through, along with the milk and chia seeds, taking care not to overmix.
Using a teaspoon, divide the batter between the muffin cases, filling them 3/4 of the way up. Place a blob of lemon curd on top of each and swirl into the mixture with a skewer (or back of a spoon).
Bake in the oven for 25-30 minutes until golden brown and springy to the touch.