For the hot chocolate: Bring the milk to a simmer in a large heavy saucepan over medium-high heat. Add the chocolate, guajillo chile, cinnamon stick and vanilla bean. Reduce the heat to medium-low. Simmer for 10 minutes, whisking constantly to develop some froth and completely melt the chocolate. Remove the chile, vanilla bean and cinnamon stick from the hot mixture.
For the whipped cream: In the bowl of a stand mixer fitted with a whisk attachment, or in a large glass mixing bowl with a hand mixer, beat the cream until soft peaks form. Add the powdered sugar and beat to stiff peaks.
Pour the hot chocolate into a mug. Dollop with the whipped cream and dust with cinnamon and chili powder. Serve immediately.