Preheat oven to 350°F.

Combine flour, oats, coconut, salt and baking soda. Stir in granulated sugar and brown sugar and mix until no clumps of sugar remain. Add melted butter and stir mixture until evenly moistened. Use your hands to make sure it is well combined or you can do this in a stand mixer.

Use about ¼ cup of crumb mixture per tart to form the base. Mound it into the middle and then press it out evenly over the base and out to the edges using your fingers to fit it well into the tart pans. For seven tarts, this should use about two-thirds of the crumb mixture. Reserve the remaining mixture for topping. Bake for 10-15 minutes or until golden brown and slightly puffed. Remove from oven and set aside to cool while you make the filling.

In a mixing bowl, whisk together sweetened condensed milk, lemon juice, egg yolks and lemon zest until well blended. Spoon mixture over pre-baked crusts (about 3 tablespoons each) and spread into an even layer. Sprinkle top with remaining crumb mixture and top with extra sweetened flaked coconut. Bake in preheated oven 15-20 minutes until lightly golden. Remove from oven and allow to cool at room temperature. Store in airtight container in refrigerator.