Preheat the oven to 375°F (190°C). Line a muffin tin with 6 paper liners.
In a large bowl, whisk together the all-purpose flour, granulated sugar, salt, and baking powder.
In a separate bowl, whisk together the melted unsalted butter, egg, whole milk, and 1 teaspoon vanilla extract until combined.
Pour the wet ingredients into the dry ingredients and stir gently until just combined; do not overmix.
Fold in 1 cup of fresh blueberries carefully to avoid breaking them.
Divide the batter evenly among the 6 muffin liners, filling each about 3/4 full.
Bake for 18 to 20 minutes or until a toothpick inserted into the center comes out clean.
Remove muffins from the oven and let them cool completely on a wire rack.
While muffins cool, prepare the whipped cream by pouring the heavy whipping cream into a chilled mixing bowl.
Add powdered sugar and 1/2 teaspoon vanilla extract to the cream.
Whip the cream using a hand mixer or whisk until stiff peaks form.
Once muffins are cooled, slice each muffin in half horizontally.
To assemble, place the bottom half of a muffin on a serving plate, spoon a generous amount of whipped cream over it, then sprinkle with fresh blueberries.
Top with the muffin top half to create a shortcake.
Repeat with remaining muffins and serve immediately.