Mix dry ingredients: In a medium bowl, stir together flour and salt. Set aside.

Cream butter and sugar: In a large mixing bowl, beat softened butter until creamy. Add powdered sugar and beat until fluffy.

Add egg: Beat in the egg until combined.

Add flour: Add the flour mixture and beat on low speed until it forms a soft, crumbly dough.

Shape & chill dough: Turn the dough out onto plastic wrap; press it into a disc. Wrap and chill in the refrigerator for at least 2 hours (or overnight) until firm.

Roll out dough: On a floured surface, roll dough to about ⅛‑inch thickness. Use a scalloped round cookie cutter to cut out rounds slightly larger than muffin pan cavities.

Press into muffin pan: Gently press each round into the wells of a muffin pan; patch any tears with scraps.

Chill shell: Chill the filled muffin pan in the fridge for about 30 minutes while oven preheats to 350°F (175°C).

Blind bake: Line shells with liners and baking weights or uncooked rice. Bake for 18–20 minutes or until edges are golden brown. Let shells cool slightly, then remove from pan and cool fully on a wire rack.

Heat cream: Warm heavy cream until just simmering around edges.

Pour over chocolate: Place chopped chocolate in a heat‑safe bowl and pour hot cream over it. Let sit for about 3 minutes without stirring.

Mix to smooth ganache: Stir mixture until chocolate melts completely and ganache is smooth. Let cool slightly until thickened but still pourable.

Fill shells: Pipe or spoon ganache into each cooled tart shell, filling to about ¾ full.

Chill tarts: Refrigerate tarts until ganache is set, about 30 minutes minimum.

Whip cream: Beat heavy cream, powdered sugar, and vanilla until firm peaks form.

Decorate: Pipe a dollop of whipped cream on each tart. Add fresh fruit or a pinch of flaky salt if desired. Serve chilled.