mix to a crumbly stage, not blended. to achieve this i like to grate the butter using a cheese grater and then mix with my hands (being careful not to just let the butter melt against the warmth of your hands). if you have a pastry cutter/blender then use this to mix the butter until only small pea-sized pieces remain. not big peas, tiny crumbly peas.
now, add in the fruit stirring gently being careful not to smash the berries to smithereens.
next, pour in the milk/egg mix a bit at a time while mixing. don't over mix, just until it's all combined. please, please don't over mix. if you haven't already 