Preheat oven to 425 degrees. Stir together mascarpone, cinnamon, and sugar in a small bowl. Cut a slit lengthwise in each date, and remove pit. Fill each date with 1 tablespoon cheese mixture. Refrigerate dates until ready to serve, up to 2 hours.
Toss almonds with oil on a rimmed baking sheet. Toast in oven until fragrant and deep golden brown, about 10 minutes; sprinkle with salt. Arrange toasted almonds, stuffed dates, and clementine segments on a serving platter.
To make this Mediterranean-inspired dessert even easier to prepare, serve the dates whole with the mascarpone mixture on the side; your guests can spoon a bit onto their plates for spreading.