Prepare Your Baking Equipment:

1. Preheat your oven to 325°F (163°C).
2. Butter and flour mini bundt molds or ramekins to ensure the cakes release easily after baking.

2. Make the Caramel Filling:

1. In a small bowl, combine toffee bits, brown sugar, cinnamon, cocoa powder, and chopped semisweet chocolate.
2. Mix well and set aside.

3. Prepare the Cake Batter:

1. In a medium bowl, whisk together flour, baking powder, and baking soda. Set aside.
2. In a large bowl, cream unsalted butter and granulated sugar for about 4 minutes, until light and fluffy.
3. Beat in the egg and mix for 2 minutes.
4. Add sour cream and vanilla, mixing until smooth.
5. Gradually add the dry ingredients to the wet mixture, stirring until just combined.

4. Assemble the Lava Cakes:

1. Add 4 tablespoons of cake batter to each prepared mold.
2. Spoon 1 tablespoon of the caramel filling into the center of each mold.
3. Top with the remaining batter, ensuring the filling is fully enclosed.

5. Bake the Cakes:

1. Bake for 20-25 minutes, or until the edges are set and the tops spring back when lightly touched.
2. Let the cakes cool in the molds for 10 minutes before carefully unmolding onto a wire rack.

6. Prepare the Icings: Chocolate Icing:

1. Mix confectioners’ sugar, cocoa powder, golden syrup, water, and vanilla extract until smooth.

Vanilla Icing:

1. Combine confectioners’ sugar, golden syrup, water, and vanilla extract, adjusting water for a drizzle-able consistency.

7. Decorate the Cakes:

1. Drizzle the chocolate icing over the cooled cakes.
2. Follow with the vanilla icing for a striking contrast.
3. Let the icings set for at least 2 hours before serving or storing.