1. Prepare the Pan and Preheat Oven:
* Preheat your oven to 350°F (175°C).
* Grease an 8×8 inch or 9×9 inch square baking pan. For easier removal and cleanup, line the pan with parchment paper, leaving an overhang on two opposite sides to act as “handles.” Lightly grease the parchment paper as well.

2. Make the Oat Crust and Crumble Mixture:
* In a large mixing bowl, combine the rolled oats, all-purpose flour, packed light brown sugar, baking soda, and salt. Whisk them together thoroughly to ensure even distribution of the leavening agent and salt.
* If using nuts, stir them into the dry ingredients now.
* Pour the melted vegan butter (or coconut oil) over the dry ingredients.
* Using a fork or your fingertips, mix until the ingredients are well combined and the mixture resembles coarse, damp crumbs. It should hold together when pressed.

3. Par-Bake the Crust:
* Reserve approximately 1 ½ cups of the oat mixture for the topping.
* Press the remaining oat mixture firmly and evenly into the bottom of the prepared baking pan. Use the bottom of a glass or a measuring cup to get a compact and even layer.
* Bake the crust for 10-12 minutes, or until it’s lightly golden and set. Remove from the oven and set aside.

4. Prepare the Vegan Caramel Filling (if making homemade):
* While the crust is par-baking, you can start the caramel. If using store-bought caramel, you can skip this step and simply ensure your caramel is pourable (warm it slightly if necessary).
* In a medium saucepan, combine the scooped thick coconut cream, light brown sugar, maple syrup (or agave), and vegan butter.
* Place the saucepan over medium heat. Bring the mixture to a gentle boil, stirring constantly to dissolve the sugar and prevent burning.
* Once boiling, reduce the heat to medium-low and let it simmer for 5-8 minutes, stirring frequently, until the caramel has thickened slightly. It should coat the back of a spoon. Be careful, as hot caramel can bubble and spatter.
* Remove the saucepan from the heat. Stir in the vanilla extract and salt. The caramel will continue to thicken as it cools. If it seems too thin, you can return it to low heat for a few more minutes. If it becomes too thick upon cooling, you can stir in a teaspoon or two of plant-based milk or hot water to reach a pourable consistency.

5. Assemble the Carmelitas:
* Once the crust is par-baked, immediately sprinkle the vegan chocolate chips evenly over the hot crust. The residual heat will help them melt slightly, creating a lovely gooey layer.
* Carefully pour or drizzle the warm vegan caramel sauce evenly over the chocolate chip layer. Use an offset spatula or the back of a spoon to spread it gently if needed, trying not to disturb the chocolate chips too much.
* Take the reserved 1 ½ cups of the oat crumble mixture and sprinkle it evenly over the caramel layer. Gently pat it down if you prefer a more compact topping, or leave it loose for a more rustic look.

6. Bake the Assembled Carmelitas:
* Return the pan to the preheated oven (350°F / 175°C).
* Bake for an additional 15-20 minutes for an 8×8 pan, or 18-22 minutes for a 9×9 pan. The topping should be golden brown, and the caramel might be bubbling around the edges.
* Be careful not to overbake, as this can make the bars dry and the caramel too hard.

7. COOL COMPLETELY (Crucial Step!):
* Remove the pan from the oven and place it on a wire rack.
* This is the most important and perhaps the hardest part: you must let the Carmelitas cool completely before cutting. This will take at least 2-3 hours at room temperature. For best results and cleanest cuts, chill them in the refrigerator for an additional 1-2 hours (or even overnight) after they’ve cooled to room temperature.
* Attempting to cut them while warm will result in a delicious, gooey mess (still tasty, but not neat bars). The caramel needs time to set.

8. Cut and Serve:
* Once completely cooled and set (preferably chilled), use the parchment paper overhangs to lift the entire block of Carmelitas out of the pan and onto a cutting board.
* Use a large, sharp knife to cut them into squares or bars. Wiping the knife clean with a damp cloth between cuts can help achieve neater edges.
* If you chilled them in the fridge, you might want to let them sit at room temperature for 10-15 minutes before cutting for easier slicing.
* Sprinkle with flaky sea salt before serving, if desired.