This dessert tastes best warm, about an hour after it comes out of the oven. It should be made the same day you intend to serve it, but the nuts and syrup may be prepared a day in advance.
Make the honeyed pine nuts: Preheat oven to 325 degrees. Combine nuts and honey in a small bowl. Spread in a single layer on a Silpat-lined rimmed baking sheet. Bake, stirring every 5 minutes, until golden brown, 20 to 30 minutes total. Season with salt. Let cool completely on sheet on a wire rack. Break honeyed nuts into 1/4-inch pieces with your fingers. (Nut pieces can be stored in an airtight container up to 3 days.)
Make the tart: Whisk eggs in a medium bowl. Bring milk, lemon zest, 1 cup granulated sugar, and 1 tablespoon butter to a simmer in a medium saucepan over medium heat, stirring to dissolve sugar. Remove lemon zest. Add semolina flour in a slow, steady stream, whisking constantly, until mixture is thick, about 2 minutes. Remove from heat.
Pour 1/3 of the semolina mixture into the eggs in a slow, steady stream, whisking slowly and constantly. Pour egg mixture back into saucepan with remaining semolina mixture. Cook, whisking constantly, for 1 minute. Transfer to a bowl. Let cool, uncovered, until ready to use.
Stir together cinnamon with remaining 1/4 cup sugar. Melt remaining 2 sticks butter in a small saucepan. Using a pastry brush, coat a 9-inch springform pan with some of the melted butter.
Place phyllo on work surface, and cover with a damp cloth. Place 1 phyllo sheet in the pan, with 1 corner of the sheet in the center. Press sheet gently against the pan, letting overhang drape over the edge. Repeat with 2 more sheets, overlapping them so the pan is completely covered and overhang extends from all edges. Brush generously with butter and sprinkle with 1/2 teaspoon cinnamon sugar. Repeat 2 more times, using 6 more sheets, brushing each layer with butter and sprinkling each layer with 1/2 teaspoon cinnamon sugar.
Pour cooled custard into phyllo-lined pan. Fold 1 sheet of overhang over custard, and brush with butter. Repeat with remaining overhang, working 1 sheet at a time. Sprinkle 1 1/2 teaspoons cinnamon sugar over the top.
Brush butter on top of each of the remaining 6 phyllo sheets. Gently crumple each sheet, and arrange it evenly over the cake to cover. Pierce cake all over with a skewer. Place on a baking sheet. Bake until golden brown, about 1 hour. Let cool in pan on a wire rack for 15 minutes. Carefully remove sides of pan. Let stand until just warm, 45 to 60 minutes.
Meanwhile, make the syrup: Bring honey, water, and lemon zest to a simmer in a small saucepan over medium heat. Cook, stirring once or twice, until mixture is runny, about 3 minutes. Remove from heat, and let stand until just warm. Remove zest when ready to use. (Syrup can be refrigerated in an airtight container for up to 1 month; reheat over medium heat until warm.)
Sprinkle nuts and confectioners' sugar on top of cake. Cut into slices, and divide among serving plates. Serve warm with a drizzle of syrup.