The night before, or ideally, several days before: Put the dried cherries in a pint mason jar and cover with the Port wine. Cover the jar with a lid and leave to sit overnight at a minimum, turning the jar from time to time to ensure all cherries are exposed. The cherries need time to soak up as much liquid as possible.
Preheat oven to 360 degrees.
Prepare a 9 x 9 inch pan by greasing and covering the base and sides with two pieces of parchment paper. Allow the paper to overhang the sides as "handles" to lift out the baked brownies.
Strain the cherries (Save the Port for future recipes or for a little glass to accompany the brownies! It's now deepened in flavor with the addition of cherry essence).
In a small bowl, whisk together flour, baking powder and salt and set aside.
In a medium size heavy saucepan, melt the butter and sugar on medium low heat, whisking frequently, until the sugar has dissolved and the mixture has a sheen and is smooth. Avoid letting the mixture simmer or foam. Thalia's instructions note that the perfect temperature to reach here is 122 degrees F - if you have a candy thermometer, feel free to use it here. (I did not, and still got great results).
In a stand mixer, whisk the eggs, cocoa and vanilla together with the whisk attachment until well blended and smooth, for two to three minutes. Scrape down the sides of the bowl several times.
With the mixer running on low, carefully pour in the butter-sugar mixture. Continue to mix until completely incorporated, again scraping down the sides of the mixing bowl with the spatula.
Add the dry ingredients all at once, and whisk one last time, just until incorporated.
With a spatula, fold in the chocolate chips and the strained dried cherries.
Pour into the prepared pan and smooth the top with an offset metal spatula.
Bake for 20-25 minutes, until just set in the middle. You don't want these to be over-baked. Start checking at the earlier time.
Remove from the oven and cool in the pan. When cool, use the parchment paper handles to carefully lift out the brownies. Cut them into squares, wiping the knife clean between slices.
Notes
This recipe is adapted from the incredible Salted Espresso Fudge Brownie recipe by Thalia Ho. I reduced the sugar and omitted the espresso powder and frosting in order to let the flavor of the Port soaked cherries shine.