For candied oranges: In a large skillet, combine sugar and 1¼ cups water. Cook over medium heat until sugar is dissolved. Add orange slices, and simmer for 10 minutes. Remove from heat, and let cool. Lightly spray a sheet of parchment paper with cooking spray. Remove orange slices with a fork, and place on parchment. In a small bowl, stir together orange syrup and 2 tablespoons orange liqueur. Set aside.

Preheat oven to 325°F. Spray a 9x5-inch loaf pan with baking spray with flour. Line pan with parchment paper, letting excess extend over sides of pan.

For cake: In a large bowl, whisk together melted butter, sugar, ¼ cup orange liqueur, poppy seeds, and orange rind. Add milk and eggs, whisking until combined. Add flour, baking powder, and salt, whisking until combined. Pour batter into prepared pan. Place candied orange slices over batter, overlapping*.

Bake for 30 minutes, and then cover with foil. Bake until a wooden pick inserted in center comes out clean, about 1 hour and 15 minutes. Let cool in pan for 10 minutes. Using excess parchment as handles, remove from pan. Drizzle cake with half of orange syrup, and let cool completely. Serve with remaining syrup.