Preheat oven to 180°C. Using a 4 cm round cookie cutter, cut out bread pieces (about 24 pieces). Oil pieces on both sides and bake in oven for 10-15 minutes until golden brown. Bring eggs to a boil in a pot of water. Boil for 4 minutes.
Rinse eggs with cold water and let cool. Peel eggs and cut in half. Remove yolks and set egg whites aside.
Blend egg yolks with lemon juice for about 10 seconds. With blender running, add melted butter in a thin stream. Add basil and mix well.
Melt remaining butter, add spinach and saute until spinach begins to collapse. Place spinach and half an egg white on each piece of bread.
Fill this with the egg yolk mixture.