Deal with the oranges first. Zest and juice one. Measure the juice, you'll need about 2/3 a cup. If necessary, you can either juice another orange, or supplement with water or other juice you may have on hand. Cut the second orange into 8 sections. Remove the peel and trim the individual pieces of orange. Reserve the orange slices to use as a garnish, Take two or three piece of reserved peel and use a sharp, flexible knife to cut away the pith such that only the peel remains. Slice the peel into thin strips.
Melt the butter, orange zest and peel in a large sauce pan or skillet over medium heat.
Add the sugar, orange juice, vanilla and salt. Stir well to combine.
If you don't want to flambe the brandy, add it now, otherwise wait until the entire dish is assembled. (optional)
The sauce will bubble and froth as it cooks. Just keep stirring and manage the heat to prevent a boil over. Eventually the sauce will smooth out and begin to thicken.
At this point you can remove the sauce from the heat and allow to cool to transfer to the fridge.