Coat 6 6-ounce ramekins with butter and then lightly flour the ramekins. I tap the flour around over the sink, which makes clean up super easy!
Melt 5 1/2 ounces of the chopped chocolate and butter in the top of a double broiler or microwave. If using the microwave, be sure to watch it carefully and remove once it's just melted so it doesn't burn.
Using an electric mixer with a whisk attachment, beat the eggs, egg yolks, and sugar together until pale and thick (size will almost double); approximately 8 minutes.
Reduce speed of mixer and add the flour.
Add the melted chocolate mixture and continue beating until glossy; approximately 5-7 additional minutes.
Divide half of the batter into the ramekins, making sure it covers the bottom of the ramekins. I use a 1 inch scoop in order to evenly divide the batter, and use approximately 1.5 scoops in each ramekin for this first layer.
Make a small pile of the chopped chocolate chunks in the middle of each ramekin, dividing the chocolate evenly between all ramekins.
Top each ramekin with the rest of the batter, dividing evenly among the 6.
Place ramekins on a jelly roll pan or cookie sheet with edges for easy transportation.
Bake for approximately 12 minutes, until just set around the edges and the center still jiggles. DO NOT overcook.
Cool for a few minutes; flip over ramekin on a plate to release the cake.