Step 1

Adjust oven rack to middle position and preheat oven to 350°F. Line 9-inch springform pan with parchment and butter pan.

Step 2

Place two whole oranges (unpeeled) in microwave safe bowl and cover. Heat on high power until oranges are very soft and liquid is beginning to pool at bottom of bowl, 6 to 8 minutes. In small bowl, stir 1 tablespoon of the juice in bottom of bowl with 1/4 teaspoon saffron threads. When oranges are cool enough to handle, slice into quarters and process in food processor until pureed.

Step 3

In large bowl, whisk sugar with eggs until combined. Whisk in vanilla. Toss almonds with baking powder in small bowl and then whisk into mixture. Whisk melted butter and saffron with juice into mixture. Whisk in orange puree.

Step 4

Pour into pan and bake until golden and a skewer inserted into the center comes out clean, about 55 minutes. Transfer to wire rack to cool 1 hour.

Step 5

Zest strips of outer peel from remaining orange and then juice orange. In small saucepan heat zest, juice, honey, and remaining 1/4 teaspoon saffron threads until warm.

Step 6

Invert cake onto serving plate and remove paper. Poke holes into cake with skewer and pour syrup over cake. Cool to room temperature and serve.