Preheat the oven to 210°C. Prepare a baking sheet for muffins.
Prepare a bowl - add eggs, caramel syrup, vanilla extract, oil, melted butter, and brown sugar. Whisk with an egg whisker until fully combined for 2-3 minutes.
Add pumpkin puree, and sour cream and mix again. Do not over-mix! Just until everything is well mixed.
Then add flour, a pinch of salt, baking powder, and spices. Whisk with an egg whisker until flour disappears - again, do not over-mix! Add a handful of chocolate chips (or more) and fold in.
If you want good-looking muffins, pour till ¾ paper muffin cup is full. For big and chunky muffins (mushroom shape) pour until the top. I added more chocolate on top. Bake for 5 minutes. Then decrease the temperature to 180° and bake for another 10 minutes or until the toothpick comes out clean.
Take the muffins out of the oven and let cool on the baking tray for 5 minutes. Then take them out of the oven, and let them cool completely.