In my experience, kids that young tend to like rather plain things and sweet things. Also, you should avoid nuts or raisins at that age as young children sometimes inhale them, which can cause severe lung problems.
This recipe might be a good choice:
BUTTERMILK POUND CAKE
3 cups all-purpose flour
¼ teaspoon baking soda
½ teaspoon salt
1 cup butter
3 cups white sugar
6 eggs
1 teaspoon lemon extract
1 teaspoon vanilla extract
1 cup buttermilk
1. Preheat oven to 325. Grease one 9 or 10 inch Bundt pan.
2. Mix together the flour, baking soda, and salt; set aside.
3. In a large bowl, beat butter with sugar until well creamed,
about 4 to 5 minutes.
4. Add the eggs, one at time, beating well after each addition.
5. Stir in the lemon and the vanilla extracts.
6. Gently mix in 1/3 of the flour mixture, then 1/3 of the buttermilk;
repeat until all the flour and buttermilk have been added; mix
only until blended, and do not over mix.
7. Pour batter into the prepared pan.
8. Bake in preheated oven for about 70 minutes, depending on
your oven and pan; check cake after 60 minutes; cake is done
when it begins to pull away from the side of the pan.
9. Cool cake in pan for 10 minutes, then turn out onto a wire rack
and cool completely.