In a small bowl, whisk together flour, cinnamon, and salt. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment, beat butter on medium speed until smooth and glossy, about 1 minute. Slowly add sugar and beat on medium until pale and fluffy, about 3 minutes. Add egg and beat in, 1 minute.

Add flour mixture and pulse mixer to start incorporating. Beat on low until completely combined, 30 seconds.

Transfer to work surface and smear several times with the heal of your hand to ensure the flour is thoroughly incorporated. Shape into a 6-inch disk, wrap with plastic, and refrigerate at least 1 hour, or, preferably, overnight.

Preheat oven to 350°F.

Butter a 9-inch fluted tart pan.

On a lightly floured work surface, roll dough into an 11-inch circle and press into tart pan. Line with baking parchment and fill with pie weights. Place tart pan on a baking sheet and bake for 20-25 minutes. Remove paper and weights and continue to bake until dry and lightly golden, 10 minutes more. Remove from oven and let cool.

Lower oven temperature to 325°F.

In a medium saucepan over medium heat, combine blueberries, crème de cassis, if using, and about half the sugar. Cook, stirring occasionally, until about half the berries have burst and the sugar is dissolved into the released liquid. Remove from heat.

Meanwhile, in a medium bowl, whisk together remaining sugar, eggs, and goat cheese until smooth.

With a slotted spoon, scoop berries, allowing the liquid to drain back into the pan, into tart shell. Pour cheese mixture over the top and smooth.

Strain remaining berry juice through a fine mesh strainer to use as a coulis for serving.

Bake 25 to 30 minutes, or until filling is set and lightly golden. Let cool 20 minutes before removing from pan and serving drizzled with coulis.