Preheat oven to 325°F.
In a bowl, mix together the flour, sugar, salt, and baking soda.
In a small saucepan, melt butter. Add water, stir and bring this buttery mixture to a boil.
Add this hot buttery mixture to dry ingredients. Using an electric mixer, mix until just combined.
Add sour cream, egg, lemon zest, and lemon juice. Beat until smooth.
Grease mini muffin tin with cooking spray. Add batter to the prepared muffin tins. Bake in the preheated oven for 10-15 minutes or until a toothpick inserted into the center comes out clean. Let them cool for 5 minutes in the mini muffin pan. Then, transfer them to the cooling rack. Let them cool to room temperature.
While they are cooling, prepare the glaze. Combine powdered sugar, lemon juice, lemon zest, milk, and melted butter. Heat for 10-15 seconds in the microwave.
Dip each mini lemon drop cake into the glaze (bottom side down). Then, return to the rack. Serve when glaze hardens.