Make the dough: In a large bowl, stir together the yeast, 1 teaspoon of the sugar, and the warm water. Let sit until foaming, 5-10 minutes. Meanwhile, in a large bowl, whisk together 4 cups (560 g) flour and the salt.
Stir the remaining 1/2 cup (100 g) sugar, the eggs, vanilla, orange zest, and almond extract (if using) into the yeast mixture. Add the flour mixture and gently stir until the dough begins to come together. Turn the dough out onto a floured surface and knead well, adding the softened butter pieces a few at a time, and adding up to 1/2 cup (70 g) additional flour as needed, until you have a suple, slightly tacky dough, about 10 minutes. You might not need all of the flour. (The kneading can also be done in a stand mixer with a dough hook, 5-7 minutes.)
Grease a large bowl with the vegetable oil, add the dough, and turn to coat. Cover the bowl with a tea towel and let sit in a warm place until nearly doubled in size, 1-1 1/2 hours. Meanwhile, preheat the oven to 350F (180C). Generously grease a 9-inch (23cm) round springform pan.
Make the topping: In a small saucepan, melt the butter over medium-low heat, then transfer to a bowl. In a second bowl, whisk together the brown sugar, cinnamon, and salt.
Gently deflate the dough with the heel of your hand. Pinch off a golf ball-size piece of dough and roll it into a ball. Dip it in the melted butter and then the cinnamon-sugar mixture, making sure all sides are coated, and place it in the prepared pan. Continue this process until the pan is lined with a single layer of dough balls. Evenly dollop the jam on top of and around the dough balls. Repeat the rolling and dipping process until all of the dough is used. If there is any melted butter remaining, drizzle it on top, then sprinkle with any remaining cinnamon-sugar mixture.
Place pan in the oven (if desired, set a parchment paper-lined baking sheet on the rack below the pan to catch any leaks) and bake until the cake is puffed and golden brown, 35-40 minutes. Let the cake cool in the pan on a wire rack for 10-15 minutes, then carefully unmold the cake and transfer to a serving dish. Serve warm.