Pastel de Tres Leches con Coco (Three Milks Cake With Coconut)

Ingredients

• Unsalted butter, for greasing pan
• 1 cup flour, plus more for pan
• 1 cup sugar
• 6 eggs
• 2 tbsp. coconut-flavored rum
• 1 (14-oz.) can sweetened condensed milk
• 1 (13.5-oz.) can coconut milk
• 1 (12-oz.) can evaporated milk
• Poached peaches in syrup, cut into eighths, to garnish