Prepare the macaron batter. Place the egg whites and granulated sugar into a mixer bowl and whisk on high speed for 2 to 3 minutes, just until stiff peaks form. Next, add the caramel emulsion or extract and whisk again for 30 seconds, just until the color and flavor is incorporated. Sift the confectioner's sugar and almond flour into a separate mixing bowl.
Add the meringue to the sifted flour and sugar. Using a spatula, fold and flatten the meringue into the dry ingredients, scraping from the bottom of the bowl to get all the ingredients incorporated. Mix and fold until the batter reaches ribbon stages and ribbons off the spatula. Transfer the batter into a pastry bag tipped with a simple, round tip.
Line two baking sheets with parchment paper or silicone mats. Pipe even-sized dollops onto the parchment paper, drawing circle guides on the back of the paper if desired. Tap the baking sheet a few times against your work surface to release any trapped air bubbles. Allow the macarons to stand at room temperature for approximately 1 hour (more for high humidity climates), allowing a thin film to form on the outside.
Preheat the oven to 320F. Bake the macarons for 18 to 20 minutes; the cookies should release from the paper/mat with ease. Allow the macaron shells to cool on the baking sheet for about 10 minutes, then transfer onto a cooling rack to cool completely. Meanwhile, prepare the filling and frosting.
For the salted caramel frosting, first whisk the softened butter for a few minutes until white in color and fluffy. Add the dulce de leche (or caramel sauce), vanilla, salt and confectioner's sugar. Whisk again for a few minutes until the frosting is fluffy. Transfer the frosting into a piping bag tipped with a simple star tip.
Prepare the chocolate ganache: place the chocolate chips and cream into a measuring cup. Microwave the chocolate for approximately 45 to 60 seconds, until the cream is hot. Stir until the chocolate is completely melted.
To assemble the macarons, first pair up the shells according to size. Pipe a ring of salted caramel frosting around the edge of the cookies, leaving a bit of space to add the chocolate ganache in the center. Sprinkle the frosting with crushed toffee candy pieces, then top with the second macaron half.
For best results, place the macarons into an airtight container and refrigerate for 1 to 3 days, allowing the cookies to 'mature' - the shells will absorb moisture from the filling and soften. When ready to enjoy, remove the cookies from the fridge for about an hour and allow the filling to soft.