Preheat the oven to 325 degrees. Spray a 12-cup bundt pan with non-stick cooking spray with flour and set aside.
In a medium bowl, stir together flour, baking powder and salt. Set aside.
In the bowl of a stand mixer, beat the butter until light and creamy. Add both sugars and beat again until fluffy. Add eggs one at a time, mixing until blended. Alternate adding in flour mixture and milk, mixing until just combined, being careful not to over mix.
Stir in toffee chips and pecans by hand, blending well. Spoon the batter into the prepared pan.
Bake for 75-80 minutes or until a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for 10 minutes, then invert onto a wire rack to cool completely.
Once the cake is cool, prepare the Caramel Drizzle as follows:
Combine the sweetened condensed milk and brown sugar in a medium, heavy–bottomed saucepan. Over medium heat, bring to a boil, whisking very frequently.
Reduce the heat under the pan and simmer gently for about 8 minutes, whisking constantly.
Remove the pan from the heat and stir in butter and vanilla. Allow the mixture to sit in the pan for about 5 minutes – then drizzle over the cake. (You will want the drizzle to still be fairly hot when you drizzle it over the cake – it does harden a little after it cools.)