Preheat the oven to 350F and line 12 muffin tins (or 24 mini muffin tins) with paper liners. Put the dates and other chopped fruit into a heatproof bowl and pour the boiling water overtop; let stand for 15 minutes, until soft. Mash it well with a fork or pour into a food processor and pulse until well blended but still a bit chunky.
Meanwhile beat the butter, oil and brown sugar in a large bowl with an electric mixer for a few minutes, until well blended and light. Add the eggs, molasses and vanilla and beat well.
In a small bowl, stir together the flour, baking powder, cinnamon and salt. Add about a third to the butter mixture, stirring or beating on low speed just until incorporated. Add half the pureed fruit in the same manner, then another third of the flour, the rest of the fruit and the rest of the flour, mixing just until blended.
Divide the batter among the prepared muffin tins and bake for 25-30 minutes (for regular-sized cupcakes) or 20-25 minutes (for mini cupcakes) until golden and the tops are domed and springy to the touch. Tip them slightly in their tins to allow steam to escape and help them cool completely.
To make the frosting: in a large bowl, beat the cream cheese and butter for a few minutes, until smooth and fluffy; gradually beat in the powdered sugar, milk and vanilla until you have a soft, spreadable consistency, adding a little extra sugar or liquid if you need it. Frost cupcakes once they have cooled completely.