Preheat the oven to 350°F (180°C). Lightly grease a 12-cavity mini bundt pan or a standard muffin pan.

Place the pitted Medjool dates and the boiling water in a food processor or blender. Let the dates soak for a few minutes, then blend until smooth, scraping down the sides as needed. Set the date puree aside.

In a large bowl, beat the softened butter and dark brown sugar for the cake until well combined and creamy.

Add the eggs, molasses, and vanilla extract to the butter-sugar mixture and mix until smooth and uniform.

In a separate bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt.

Add the dry ingredients to the wet mixture and mix briefly (about half the way), then add the blended date mixture. Mix just until the batter is combined—avoid overmixing.

Fill each prepared pan cavity about three-quarters full with batter.

Bake for 18–25 minutes, or until a toothpick inserted into the center of a cake comes out clean. Remove from the oven.

While the cakes bake, make the toffee sauce: in a large saucepan combine the butter, dark brown sugar, and heavy cream. Bring to a gentle boil over medium-high heat, stirring occasionally. Boil softly for 7–9 minutes (or until the sauce thickens and reaches about 220°F / 105°C). Remove from the heat and stir in the vanilla extract and salt.

Let the cakes cool in the pan for a few minutes (about 3–5 minutes), then carefully remove them from the pan while they are still warm.

To serve, place each cake upside down on a plate, spoon warm toffee sauce over the top, and sprinkle with chopped pecans if desired. Serve immediately.