Prep: Start by preheating the oven to 425 degrees F.
Then, coat an 8 x 3-in. cake pan with nonstick spray. Line the bottom with parchment paper and spray the paper. Also, have a larger roasting pan ready.
Cake batter: In a large bowl, beat all the eggs with a handheld mixer on high for 7 minutes, or until the egg mixture has tripled in size.
Then, melt the chocolate chips and butter together in a small pan on the stove over medium-low heat; stir until well blended.
After that, whisk the chocolate and butter mixture into the bowl of eggs until blended. Proceed to pour into the prepared cake pan.
Bake: Next, place the large roasting pan in oven and place the filled cake pan inside. Pour boiling water into roasting pan to come halfway up sides of cake pan. Cover cake pan loosely with foil; bake 40 minutes. (Cake looks soft but sets when cold.)
Cool: When baking is complete, cool the cake in pan on a wire rack. Cover and refrigerate 3 hours, or until firm. Invert on serving platter; shake down sharply to release cake. Peel off parchment paper.
If desired, lay five 3/4-in.-wide strips of paper 3/4 in. apart on cake. Sift cocoa between strips; carefully lift paper. Repeat in opposite direction, this time sifting on powdered sugar.
Decorate: First you'll need to print off a Chevron Pattern that seems to fit the size of your cake. I could have done a smaller pattern, however it's difficult to get nice crisp edges when the pattern is too small. After you print off your pattern, cut spaces between the pattern, leaving one edge intact. After you've cut all the white space out, tape the other edge together with one long strand of tape on the front and back. This will give you 2 solid edges to hold on to. Lay it over the cake and sift powdered sugar on top, being mindful to stay as still as possible! {We did this with 2 people- one held the Chevron pattern, the other sifted.}
After you're pleased with the amount of sugar on top, carefully lift the Chevron pattern up and away from the cake. VOILA! Slice, serve and enjoy!