Preheat the oven to 325F / 175C and line up an 8-inch baking sheet with parchment paper.
In a large bowl, beat together the cream cheese and butter until well combined. Beat in the brown sweetener until lightened and fluffier, about 3 minutes.
Add the eggs one at a time, beating after each addition. Scrape down the bowl and beaters as needed. Add the vanilla extract.
Add the almond flour, spices, baking powder, and salt all at once and beat in until well combined. Spread the batter in the prepared baking pan and bake 55 to 65 minutes, until the top is set and firm to the touch.
Remove and let cool in the pan for at least 20 minutes before flipping out onto a wire rack to cool completely.
Mascarpone Cheese frosting
Add the softened cream cheese in a large mixing bowl using a hand mixer. Beat for about 2-3 minutes or until fluffy. Try not to over mix.
Add Heavy cream and beat for more 4 minutes.
Incorporate the sweetener and vanilla extract. Mix well until you get a creamy and fluffy frosting.
Spread over the cooled cake. Drizzle with toasted walnuts and serve.