Preheat oven to 375 degrees F/190 degrees C.
Fit pastry rounds into tart pans; place all on baking sheets and place in freezer until ready to fill.
Combine egg yolks, sour cream, cheese, salt, and pepper in a mixing bowl. Spoon equal portions into each tart shell. Top with sliced tomatoes. Bake until crust is browned (30-40 minutes).
While tarts are baking, boil remaining eggs for four to six minutes (depending on level of preferred doneness).
Serve each tart with a sliced egg on top; garnish with chives.