This fudge comes together very quickly; you just need some patience while it sets (also between layers). First, line a baking pan or dish of about 16 × 24 cm (6 × 9½ inches) with parchment paper.
Place the chocolate and sweetened condensed milk in a small saucepan. Melt the chocolate over low heat until you have a smooth mixture.
Once all the chocolate has melted, add the vanilla extract and pecans. Stir well (and quickly) to combine, then pour the mixture into the parchment-lined pan. Spread evenly with a spatula and place the pan in the refrigerator.
Only once the chocolate fudge layer has cooled completely and become much firmer should you start on the caramel layer.
For the caramel, add all the ingredients to a saucepan. Over low heat, stir regularly until the butter and sugar have melted. Then you can increase the heat slightly. The longer it cooks, the thicker it becomes. Remove the pan from the heat when the caramel is almost thick enough. As it cools, the caramel will firm up even more, so don’t let it cook for too long.
Pour the caramel over the chocolate layer and spread evenly. Sprinkle the pecans over the caramel and use a spatula to gently press them in. Absolutely do not do this with your hands, the caramel is extremely hot!
Place the pan back in the refrigerator and let it chill for several hours (I left it in overnight) until firm enough to cut into squares. Use a very sharp knife for this.
How to store
Stored in an airtight container, the fudge will keep well for at least 3 weeks.