To make the truffle centers:

1. Combine the Bailey’s, heavy cream, salt and butter in a heatproof bowl and microwave on full power for 45 seconds. The mixture should boil a bit.
2. Carefully remove the hot bowl from the microwave and add the chopped chocolate. Allow the chocolate to stand in the hot mixture for 30 seconds, then stir gently to melt everything together until smooth.
3. Refrigerate the truffle mixture for 2 hours or until firm. Once it has completely chilled, divide the truffle mixture into 4 equal balls. They don’t need to be perfectly smooth, so long as they are round in shape and mostly all the same size. I like using a small cookie scoop and heaping it up. You should have about 1 1/2 TB for each ball.
4. Set the finished truffles on a small plate and store them in the freezer until you need them.

To make the cake:

1. Preheat the oven to 350 degrees, and butter the insides of four 10 ounce ramekins. Dust the greased ramekins with cocoa powder and tap out the excess. Alternatively, you can use baking spray. Set the prepared ramekins aside.
2. Stir the vanilla extract and cocoa powder into the hot coffee, whisking to dissolve well. Set aside.
3. In a large mixing bowl, combine the sugar, salt, baking soda, egg and egg yolk. Whisk well for one minute, the mixture should be more pale and thick.
4. Add the buttermilk and oil, and mix for another minute. Add the flour and whisk well for 2 minutes. The batter should thicken up a bit more as you mix in the flour.
5. Pour in the coffee/cocoa/vanilla mixture and the melted chocolate and gently mix for one minute until well combined. Use a spatula to scrape the sides and bottom of the bowl and make sure everything is incorporated.
6. Add 1/2 cup of cake batter to each ramekin. You will have half of the batter leftover, which you can bake into cupcakes or reserve in the fridge for a few days and make more lava cakes later.
7. Set the ramekins on a baking sheet and bake for 23-25 minutes, or until the edges of the cakes spring back lightly when pressed. The centers of the cakes should still be wiggly, but not soupy.
8. NOTE – if you’re baking the leftover batter into cupcakes, bake them for 26-28 minutes, or until the tops spring back lightly when you press them.
9. Remove the ramekins from the oven and carefully press a truffle ball into the center of each one. A small amount of cake batter should rise up and nearly cover the truffle. Do not press the truffle to the bottom of the ramekin.
10. Return the ramekins to the oven and continue to bake for an additional 5 minutes to melt the centers and finish baking.
11. Allow the cakes to cool for 15 minutes before turning them out to serve. Run a butter knife around the edges of the cakes before inverting them onto plates.
12. Garnish with powdered sugar and/or vanilla ice cream and serve warm.