Pre-heat oven to 350 degrees. Grease and flour bundt pan and set aside.In a stand mixer, cream butter and sugar. Add eggs, salt, vanilla, lemon juice, and lemon zest. Mix until incorporated. Add flour and heavy cream. Mix again.Remove 3 cups of batter from the bowl and place into another bowl. Add cocoa powder and tablespoons of milk. Mix until incorporated. Grease and flour a bundt pan. Place 1/3 of the chocolate batter in the pan, filling it around the middle part. Then spread down 1/3 of the vanilla batter. Repeat 2 more times so that there are 3 layers of chocolate and 3 layers of vanilla.Bake for 60-70 minutes. Cool on a wire rack. Invert cake on to a plate or cake stand.
Ganache
Place chocolate and heavy cream in a microwave safe bowl. Microwave for about 45-60 seconds. Remove. Mix chocolate with a spoon until it is fully melted. Add corn syrup. Drizzle ganache onto the cake.