Preheat oven to 170°C fan forced. Grease a 20cm Bundt tin with non-stick spray.
In a large bowl, sift together the flour, baking powder, bi-carb soda, sugar and salt.
In another bowl, mix together the egg replacer and water, whisking for 20 seconds to remove any lumps. Add milk, vinegar, margarine and vanilla. Mix well.
Add wet ingredients to the dry ingredients and beat with an electric mixer on medium-high speed until light and fluffy for approx. 2 minutes.
Pour mixture into cake tin and bake in centre of oven for approx. 40-45 minutes or until the top springs back when lightly touched.
Allow to cool in the pan for at least 20 minutes before transferring to a wire rack to cool completely.
For chocolate drip, break the chocolate into a glass bowl with the coconut oil. Microwave in 30 second bursts until melted. Mix thoroughly and allow to cool slightly before pouring over the cake.