Preheat oven to 350 degrees F. Butter and flour a 10- or 12-cup Bundt pan and set aside.

In a small saucepan, combine the butter, cocoa powder, espresso powder, salt, and water and put over medium heat. Cook until just melted and combined, stirring occasionally. Remove from the heat and set aside.

Combine the flour, sugar, and baking soda in a large bowl and whisk to blend. Add half of the melted-butter mixture and whisk until completely blended (it will be very thick). Add the remaining butter mixture and whisk to combine. Add the eggs one at a time, whisking each to blend completely before adding the next. Whisk in the Greek yogurt and vanilla until smooth.

Pour the mixture into the prepared pan and bake until a toothpick inserted into the center of the cake comes out clean, 40 to 45 minutes.

Let the cake cool in the pan for 15 minutes and then invert onto a rack. Once the cake has cooled to room temperature, drizzle with chocolate glaze.

Combine all ingredients in a saucepan. Heat over medium heat, stirring constantly, until the chocolate is melted. Remove from heat and let cool and thicken for 5-10 minutes (or until the glaze reaches your desired consistency). Then drizzle over the chocolate cake.