Preheat your oven to 350°F (175°C).
Grease and lightly flour a bundt cake pan so the cake releases easily.
In a saucepan over low heat, combine butter, cocoa powder, and the warm water or coffee; stir until melted and smooth.
Remove the chocolate mixture from heat and let it cool slightly.
In a separate bowl, whisk together the dry ingredients: keto flour blend, powdered sweetener, baking soda, and baking powder.
In a large bowl, whisk the warm chocolate mixture with eggs, heavy cream, vinegar, and vanilla until smooth.
Gradually add the dry ingredients to the wet mixture, stirring gently until mostly combined; do not overmix.
Pour the batter into the prepared bundt pan and smooth the top.
Bake at 350°F (175°C) for 5 minutes, then reduce oven temperature to 325°F (160°C) and continue baking for about 35–40 minutes, or until a toothpick inserted into the center comes out mostly clean.
Allow the cake to cool completely in the pan before turning it out onto a cooling rack.
To make the glaze, heat the heavy cream until just warm (do not boil), then pour it over the chocolate chips and butter in a bowl. Let sit briefly; stir until smooth and glossy.
Stir in the vanilla, then drizzle the glaze over the cooled bundt cake. Let set before slicing.
Recipe Info