Preheat your oven to 325 degrees F and spray a 12-cup Bundt pan generously with non-stick baking spray with flour.

In a medium bowl, combine the all-purpose flour, baking powder, and salt. Whisk until well blended.

In the bowl of a stand mixer, beat the softened unsalted butter on medium speed until light and creamy, about 2-3 minutes.

Gradually add in the packed light brown sugar and granulated sugar to the creamed butter and continue to beat until fluffy and pale, another 2-3 minutes.

Add the large eggs one at a time, mixing each one in until fully incorporated before adding the next.

Alternate adding the flour mixture and the whole milk to the mixing bowl, starting and ending with the flour mixture. Mix until just combined.

Gently fold in the milk chocolate toffee pieces and chopped pecans by hand using a spatula.

Spoon the batter into the prepared Bundt pan, filling it about two-thirds full.

Bake in the preheated oven for 75 to 80 minutes, or until golden brown and a toothpick inserted into the center comes out clean.

Remove the cake from the oven and let it cool in the pan for about 10 minutes.

Carefully invert the cake onto a serving plate.

In a saucepan over medium heat, combine the sweetened condensed milk and packed light brown sugar. Stir frequently until it comes to a boil, then reduce to a simmer for about 8 minutes.

After simmering, stir in the unsalted butter and vanilla extract until completely smooth and melted.

Drizzle the warm caramel mixture generously over the cooled cake.