In a medium bowl, combine the flour, brown sugar, butter, and cinnamon, mixing with your fingertips until the mixture is lumpy and holds together when pinched. Set aside.

Position a rack in the lower third of the oven and heat the oven to 350 degrees F. Grease and flour a 9-inch springform or round cake pan; set a round of waxed paper or parchment in the bottom of the pan.

Process the hazelnuts with 2 tablespoons of the sugar until the mixture is powdery and the nuts are finely ground. Sift the flour, baking powder, and salt onto a sheet of waxed paper; pour the ground hazelnuts on top of the dry ingredients and set aside.

Using an electric mixer, preferably with a paddle attachment, beat the butter at medium speed until creamy and smooth, about 1 minute. Add the remaining sugar and continue to beat until light and fluffy, about 3 minutes, stopping the mixer to scrape down the sides of the bowl as needed. Add the eggs one at a time, beating well after each addition. Add the vanilla. With the mixer on lowest speed, gradually add the flour-nut mixture, blending each addition just until incorporated and stopping the mixer to scrape down the sides of the bowl as needed. Spoon half of the batter into the pan and scatter half the pineapple chunks (about 20) over it, gently pressing them into the batter. Spoon the remaining batter over the pineapple, smooth the surface evenly with a rubber spatula, and scatter the remaining pineapple over the top, gently pressing the chunks into the batter. Sprinkle the streusel over the top.

Bake until the cake is golden on top and springs back without leaving an impression when gently pressed in the center and a toothpick comes out clean, not sticky, 45 to 55 minutes.

Set the cake in its pan on a rack to cool for 10 minutes. Gently tap the pan on the counter to see if the cake is releasing from the sides. Set another rack on top of the cake, invert it, and carefully remove the pan (if using a springform pan, unclasp it and remove the bottom). Lay the other rack on the cake again and invert it so the streusel side is up. Let cool completely. Just before serving, put the confectioners' sugar in a fine sieve and lightly dust the cake, if you like.