Add flour and nuts. Mix with hands until crumbly. Reserve 1 cup for topping.
Press remainder into miniature muffin tins lined with muffin papers.
Bake 12-15 minutes. Add egg, milk, lemon juice and vanilla. Put about 1 teaspoon filling into each cooled muffin cup. Sprinkle with reserved crumbs. Store in airtight container in refrigerator.