Preheat oven to 180 degrees. Grease and dust a bundt pan well.
Whisk together the dry ingredients in a bowl and set aside.
Rub the zest into the sugar. Add butter onto it and beat till fluffy.
Add one egg at a time and beat after each addition.
Add the lemon juice and beat briefly.
Add half the dry ingredients and half the buttermilk and fold in well.
Add the remaining dry ingredients and buttermilk and fold till all combined.
Finally fold in the chia seeds.
Pour into the pan and bake for 40-45 minutes till the cake is done.
Cool in pan for 10 minutes, before flipping onto a cooling rack. Cool completely before slicing and serving.