In a large bowl, whisk together flour, baking powder, salt, and sugar. Scatter butter pieces on top and use a pastry blender to cut the butter into the flour until there are no pieces bigger than a pea. Using your fingertips if necessary to make sure butter is mixed in enough.
In a medium bowl, whisk together the eggs, heavy cream, and vanilla extract. Pour liquid mixture over flour mixture. Scatter chocolate chips and walnuts on top. Stir to form a dough.
Lightly flour a work surface and place dough in middle. Knead lightly for about 1 minute, sprinkling dough with flour as needed to prevent sticking. Divide dough into 2 pieces and form each into a disk about 8 to 9 inches across. Wrap each disk in wax paper and refrigerate for 20 minutes.
Preheat oven to 400 degrees and line two baking sheets with parchment paper.
Remove dough from refrigerator and cut each disk into 6 wedges. Carefully move them to baking sheets using a spatula, placing 6 scones on each sheet. Bake scones for 18 to 20 minutes. Place baking sheets on cooling rack and after 1 minute transfer scones from baking sheets directly onto wire racks to cool.
To make topping, place caramels, milk, and salt in a small heavy-bottomed saucepan over moderately low heat. Cook until caramels completely melt, stirring occasionally. It will take about 9 to 10 minutes for them to melt. Bring to a gentle simmer, add the vanilla extract, and simmer for 1 minute. Use immediately.
Spoon Turtle Topping on top of scones and sprinkle with walnuts.