Preheat the oven to 350 degrees F. Grease bottom and sides of one 9 x 5-inch loaf pans; dust with flour, tapping out excess. Line the bottom with parchment paper.
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter, ricotta and 1 ½ cups sugar until light and fluffy, about 3 minutes.
With the mixer still running, beat in the eggs, one at a time. Add the vanilla, orange zest, and Amaretto until combined. Add the dry ingredients, a small amount at a time, until just incorporated.
Pour the batter into the prepared pan and bake until a toothpick comes out clean and the cake is beginning to pull away from the sides of the pan, about 45 to 50 minutes. Let cool in the pans for 10 minutes before removing loaf to a wire rack on top of a baking sheet.
While the loaf is cooling, make the orange syrup in a small saucepan over medium heat.
Stir together the orange juice and sugar until the sugar is completely dissolved. Once dissolved, continue to cook for 3 more minutes. Remove from the heat; set aside.
Use a toothpick to poke holes in the tops and sides of the warm loaf. Brush the top and sides of the loaf with the orange syrup. Let the syrup soak into the cake and brush again. Let the cake cool completely.