Preheat the oven to 400°. In a large bowl, sift the flour with 1/2 cup of the sugar and the baking powder. Add the orange zest and salt and scrape the seeds from the vanilla bean into the bowl. Cut in the 1 1/2 sticks of butter until the mixture resembles coarse meal. Add the cream and mix until a dough forms.
On a lightly floured surface, roll out the dough to a 3/4-inch thickness. Using a 2-inch round biscuit cutter, stamp out 10 rounds. Set the rounds on a baking sheet and refrigerate for at least 15 minutes and up to several hours.
Brush the rounds with the melted butter and sprinkle the remaining 1 tablespoon of sugar on top. Bake the shortcakes for about 20 minutes, or until golden all over. Transfer to a rack and let cool for at least 15 minutes.
Scrape the seeds from the vanilla bean into a small bowl and stir in 3 tablespoons of the sugar. Add the strawberries and toss. Refrigerate for 1 hour.
In a medium bowl, whip the cream with the remaining 1 tablespoon of sugar and the vanilla extract. Cut the shortcakes in half and set the bottoms on plates. Top each with a dollop of whipped cream and a large spoonful of strawberries. Cover with the shortcake tops and serve at once.
The shortcakes can be baked up to 4 hours ahead.