Pre-heat the oven to 375 degrees. Butter and line a round 7", 8", or 9"cake pan with parchment paper. I have made this cake with all 3 of those sizes and they all work. In this post, the pictures have a 7" cake to fit the cake stand and cake plate used.
Melt butter in medium sauce pan. Turn the heat off, and add the chocolate chips. Let the chocolate sit for a minute in the hot butter, then whisk together until the chocolate is smooth.
Add the sugar, salt, and vanilla into the chocolate mixture, and whisk to combine. Then, add the three eggs, and whisk until the egg is incorporated fully.
Stir in the cocoa powder completely, and scoop the batter into the prepared cake pan. Spread the cake evenly.
Bake at 375° for 25 minutes or till toothpick comes out clean. I feel like I have to let the cake bake an extra few minutes when I use the smaller, 7" cake pan, so use the toothpick method and make sure it is set. Let cake cool in the pan for about 10 minutes, then transfer to a cooling rack to cool completely.
Melt the butter for the glaze in a small sauce pan, turn off the heat, and then pour in the chocolate chips. Let the chocolate melt for a minute before stirring it smooth. Pour the ganache over the cooled cake, and let it set.