In a food processor, combine the flour, salt, and sugar. Pulse together until mixed. Cut butter into cubes and add to the mixture, pulsing until the texture resembles coarse crumbs.

Divide the dough in half, flatten each portion into a disk, wrap tightly in plastic wrap, and refrigerate for 1 hour.

Wash and slice the plums, toss with sugar and cinnamon, and let sit for about 10–15 minutes to create a flavorful filling.

Preheat the oven to 375°F. Roll out one disk of chilled dough, fit it into the jelly roll pan, poke holes in the bottom, spread preserves, and add the plum filling.

Brush the crust's edges with melted butter, bake for 50–60 minutes until golden and bubbling.

Allow the pie to cool completely for at least 30 minutes, then serve warm or at room temperature, optionally with ice cream or whipped cream.