1Preheat the oven to 350°F. In a medium bowl, stir together the flour, baking powder, spices, and salt. In a larger bowl, beat the butter and sugar for 3-4 minutes, until light and fluffy. Add the eggs one at a time, beating well after each, scraping down the sides of the bowl whenever it needs it. It may look separated - that's OK.
2Pour the milk into a measuring cup and add the vanilla. Add about a third of the flour mixture to the butter mixture and stir it in by hand or with the electric mixer on low speed, just until it’s combined. Add about half the milk in the same manner, then another third of the flour, the rest of the milk, and the rest of the flour, mixing just until the batter is blended.
3Divide the batter between two buttered or greased 8 or 9-inch cake pans and bake for 30-35 minutes, until the cakes are golden and the tops are springy to the touch. Invert onto a wire rack to cool completely before frosting.
4To make the penuche icing, melt the butter in a small saucepan (if you want browned butter, let it stay on the heat after it melts, until it foams, then starts to turn golden and smell nutty); pour into a mixing bowl and set aside to cool slightly. Put the brown sugar into the same saucepan along with the cream; heat, stirring, until it starts to bubble and the sugar has melted. Scrape it into the bowl with the butter, add half the icing sugar and beat until smooth.
5Add the remaining icing sugar and beat until smooth; add a little extra sugar or cream if it needs it to achieve a spreadable consistency. Spread over the cooled cake layers.